The point of this point is to discuss the idea of having a resource that is based on landing critical hits. I have a story concept for it in mind, but will not be discussing it in this thread at the moment.
I wanted to pick the minds of people who have created things for D&D before, as I never have before. With the obvious issues of people trying to abuse the Luck feat, the Halfling racial trait that rerolls 1s, and multi-classing to give yourself better chances at critical hits put aside, what do you think about a subclass for the rogue that gains a resource to perform abilities when they land a critical hit.
The flavor of the subclass is to be hyper nimble, the maneuvers they can perform are hyper agile and some of them rely on the dexterity modifier or use it in some way. As such, they are restricted to finesse weapons and are not allowed to wear heavy armor to perform the maneuvers. That may be too restrictive for D&D, but I'm just spit-balling at the moment.
The bare-bones idea i have is the rogue can gain this resource whenever they roll a critical hit against an enemy. This resource they gain is capped at 5 charges and can be spent (1 at a time or multiple at once) to perform a special maneuver that gives the character's attack a little more oomph. For example, you can spend one charge to blink behind an enemy and if the enemy fails a perception check you get advantage on your attack roll against them. This would only be usable once per turn (in the event you multi-class to get multiple attacks per turn or action surges)
I know rolling a 20 on an attack roll doesn't happen all that often, but the subclass will grant abilities to slightly increase the crit window (similar to how the Champion archetype can get 19-20 or the Hexblade's Curse gives the 19-20 crit window as well), and toying with the idea that the subclass can gain a charge if they deal the killing blow to a target. Though, one downside to that is i can see some players worrying about kill stealing.
In my mind, the class is purely physical, they don't get any spell casting abilities, but some of their maneuvers allow them to perform some spell-like abilities (Like a modified Misty step for 1 charge in the ability described above or a modified Steel Wind Strike if they use all 5 charges at once.)
The charges can be retained after a battle and carried into the next one, but the player would lose half of their accumulated charges (rounded down) on a short rest and all of them after a long rest. I don't know of any out-of-combat abilities yet the charges could be used for, but I'm still in the early stages of this idea.
Now I understand this subclass wouldn't be viable for all games. At first glance it appears to be geared more for a combat-heavy campaign. However, this is a game where you can play any race/class/etc however you want, so there could be a place for it.
As i said at the beginning of the post, I'm temporarily ignoring the idea of multi-classing to make things a bit simpler at the beginning. After I get this idea nailed down, I'd start looking into how multi-classing can break this.
The ideas you have sound fine but you're still missing the most important details. If there's one thing the 5e designers have learned throughout the playtesting process is that the most successful subclasses are the ones that have a story that resonates with people and mechanics that tie into that story. There's already plenty of official and unofficial subclasses with interesting mechanics; you have to convince me to want to create a character with yours.
Start thinking about why this subclass exists. What's their place in the D&D world? Is this fighting style old or new? Regional? Invented by a specific race?
Also, you have to give it some non-combat features. Combat's just 1/3 of the game and no one class or subclass leans 100% towards combat, interaction or exploration. If you think it "wouldn't be viable for all games" you need to rethink your approach. Turn to existing Rogue and Fighter subclasses for inspiration.
You probably want to give the subclass at least one feature that gives it reliable combat utility; you could go an entire combat without seeing a critical hit. It doesn't have to be as strong as the tricks it can do on a crit, but without something else to rely on it's too hit-or-miss. Compare to Assassins: they get a huge buff if they get surprise (unreliable, might not happen on any given session) but still have a smaller more reliable benefit any time they beat their opponent's initiative. And despite being known for Assassinate, they get strong interaction/exploration abilities too.
The flavor of the subclass is to be hyper nimble, the maneuvers they can perform are hyper agile and some of them rely on the dexterity modifier or use it in some way. As such, they are restricted to finesse weapons and are not allowed to wear heavy armor to perform the maneuvers. That may be too restrictive for D&D, but I'm just spit-balling at the moment.
So... thief? The thief subclass is modeled after the original thief-acrobat of D&D, and they're all about using their Cunning action to do agile, hyper-nimble actions, tumbling around the battlefield. Sounds like you are just hard coding different tricks into concrete mechanics. As for finesse and armor... isn't that the rogue in general already?
I feel like you're just suggesting things that the rogue can already do, but unreliably with the crit-hit mechanic.
The ideas you have sound fine but you're still missing the most important details. If there's one thing the 5e designers have learned throughout the playtesting process is that the most successful subclasses are the ones that have a story that resonates with people and mechanics that tie into that story. There's already plenty of official and unofficial subclasses with interesting mechanics; you have to convince me to want to create a character with yours.
Start thinking about why this subclass exists. What's their place in the D&D world? Is this fighting style old or new? Regional? Invented by a specific race?
Also, you have to give it some non-combat features. Combat's just 1/3 of the game and no one class or subclass leans 100% towards combat, interaction or exploration. If you think it "wouldn't be viable for all games" you need to rethink your approach. Turn to existing Rogue and Fighter subclasses for inspiration.
You probably want to give the subclass at least one feature that gives it reliable combat utility; you could go an entire combat without seeing a critical hit. It doesn't have to be as strong as the tricks it can do on a crit, but without something else to rely on it's too hit-or-miss. Compare to Assassins: they get a huge buff if they get surprise (unreliable, might not happen on any given session) but still have a smaller more reliable benefit any time they beat their opponent's initiative. And despite being known for Assassinate, they get strong interaction/exploration abilities too.
Maybe I failed to word it properly, but the post was meant to focus on the charges as a resource more so than the whole subclass. I am thinking of out of combat utilities for the subclass and have a story in mind, but just picking peoples minds on how the resource would work. I understand and agree with everything you mentioned though, so thank you for your comments.
So... thief? The thief subclass is modeled after the original thief-acrobat of D&D, and they're all about using their Cunning action to do agile, hyper-nimble actions, tumbling around the battlefield. Sounds like you are just hard coding different tricks into concrete mechanics. As for finesse and armor... isn't that the rogue in general already?
I feel like you're just suggesting things that the rogue can already do, but unreliably with the crit-hit mechanic.
I don't agree with the comparison to thief. The resources, when spent, mostly enhance the attacks the player can do, similar to how a gunslinger or a battle master can spend a grit/superiority die to do something. The only difference is they have to earn their charges, which allows for a stronger effect when the charges are used.
In comparison, a Thief is allowed to use their cunning action to perform a sleight of hand check to disarm traps or open doors, they're given the ability to jump further and climb without using extra movement, they can effectively cut their movement in half for advantage on stealth checks, they can use magic items that aren't meant for them. The only thing Thieves have that I can see clashing with the "hyper nimble" I suggested is they get to have 2 turns per round after level 17.
Again, maybe I worded my initial post poorly. Perhaps I should've said hyper nimble in combat or something.
In response to the finesse weapons and heavy armor restriction:
It's a requirement to be able to use the abilities granted by the resource, not for the subclass in general (though if a player doesn't use it they'll hurting themselves in the long run.. the restriction could be worded better but that's what rough drafts are for)
It's to prevent people from doing this while using a greatsword and chain mail to make them harder to hit. (This mainly comes into effect when multiclassing, which I said I was avoiding at the moment, but I have already thought of a couple of ways muticlassing would make this way too strong).
I rarely go out of my way to say something like this. But the idea sounds just plain bad, like some awful hybrid between World of Warcraft Rogues and Diablo 2 Assassin classes. You should figure out the story concept of the character before the mechanics, or you are doomed to a very sad result.
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"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
I rarely go out of my way to say something like this. But the idea sounds just plain bad, like some awful hybrid between World of Warcraft Rogues and Diablo 2 Assassin classes. You should figure out the story concept of the character before the mechanics, or you are doomed to a very sad result.
Thanks for your opinion, but there's a better way to say this. I have a story concept in mind, I wasn't making this thread to 100% flesh out the character. I wanted opinions on using a resource mechanic based on landing critical hits.
Cunning Action... not being nimble? I've seen rogues tumble past enemies, backstab them, before running up a wall and perching there like a spider. Being nimble is pretty much the defining definition of about half the basic rogue's abilities. Maybe we're having an issue with the definition of the word nimble.
So, lets start with this. Forget describing the class in general. Start with describing your charges and exactly what it would allow. Don't just say teleport - there's already several ways to do so. Lets start with details. What are you trying to do besides critical hits and something teleporty?
You do remember that Cunning Action is a rogue trait, not specific to any one subclass, right? I was saying the claim that what I was suggesting was basically the Theif subclass reworked was not accurate. I never said anything about Cunning Action itself.
If you read my original post completely:
The bare-bones idea i have is the rogue can gain this resource whenever they roll a critical hit against an enemy. This resource they gain is capped at 5 charges and can be spent (1 at a time or multiple at once) to perform a special maneuver that gives the character's attack a little more oomph. For example, you can spend one charge to blink behind an enemy and if the enemy fails a perception check/save you get advantage on your attack roll against them. This would only be usable once per turn (in the event you multi-class to get multiple attacks per turn or action surges)
An example for another use could be to spend all 5 charges at once to gain the ability to pick X number of targets equal to your dexterity modifier within a range. The charges spent allow you to quickly move between these targets, making attack rolls against each of them and on success dealing a proportionate amount of damage. (I am aware there is a 5th level spell (Steel Wind Strike) that accomplishes this same effect, though the damage of the charged attack will not be the same as the spell). The tradeoff is the act of doing so causes a great deal of strain on the body and the player has to make a CON save or their speed is reduced to 0 for the following turn. The effects of using these charges could be modified as abilities in higher levels of the subclass.
I'm still in the early stages of this idea, so I don't have a whole slew of ideas prepared for what frenzy charges can be used for, however a possible minimum use and maximum use example have been provided.
Obviously none of this is set in stone and a good amount of thought still has to go into what the damage numbers would be.
The largest hurdle you will have to clear is that of getting no charges. There is a decent chance you could go multiple play sessions without seeing a crit, even with an increased crit range involved. You don't see much in the way of 'charge up' mechanics in any classes because they are unreliable. Unreliable is incredibly frustrating when you are waiting for something special to trigger and then potentially have it happen in a low importance fight. Party takes a rest and there goes the charge.
Suggestions on functionality would be to avoid the 'Nova effect' such as using all of the charges in one go for massive damage. Set caps on how many can be used in a turn dependant on level perhaps similar to the monk way of the four elements. Have some reliable way to get some charges, ie always have a single charge after a long rest, sacrifice a HD for a charge after taking damage. Try to avoid to strictly relying on the whims of fate to make the class features function.
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"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
6 levels of Shadow Monk - when in dim light or darkness you can teleport 60 feet to another area in dim light or darkness and gain advantage on the next attack. This is a bonus action and costs nothing so basically meaning during a dungeon crawl or night-time you're guaranteeing a sneak attack on every turn.
If you take a 1 level dip into Sorcerer - Wild Magic you get "tides of chaos" which lets you give yourself advantage on an attack roll, ability check or saving throw. Once used takes long rest to recharge but it can also be recharged by using a spell of 1st level of higher - you immediately roll on wild surge table for a random effect that can be horrible, good, inconvenient or humorous. Spells to consider are Colour Spray (blinds enemies for a round, blinded enemies grant advantage to all attacks against them) and I definitely recommend Sleep spell. If you put the target to sleep, your next attack if they've not been woken up by somebody else, will not only be with advantage but, melee attacks on sleeping people count as auto-crits. If you take 3 levels you can have Quicken Spell metamagic and take 2nd-level spell Hold Person.Quicken Spell will let you cast your sleep/hold as a bonus so you can still attack right away with your action. Hold Person paralyses the target granting advantage to hit and if you hit in melee it's an auto-crit.
Consider 2 levels of Ranger. You get a fighting style and for a rogue I'd recommend Archer only if you rely on ranged attacks otherwise pick Dueling for the +2 damage. Rogue's are skirmishers and not much use relying on your AC, the idea is get in hit and get away. Only consider boosts to AC if you're a swashbuckler subclass which would not be the best choice for your intended build. You also get ranger spellcasting. You get 2 spell slots and can choose Zephyr Strike which is actually brutal when wielded by a Rogue. It's a bonus action so no loss of attacks, lasts a minute during which time your movement doesn't risk opportunity attacks which is great for rogues plus once during that minute, you can give yourself advantage on an attack which, if it hits, deals extra 1d8 damage and you can then move 30 ft, even if you miss. You can use the spell twice since you get 2 spell slots. Another good spell is hunter's mark for the extra 1d6 damage which is useful because if you do crit it gets rolled twice too. Also a good way to make up for possibly losing a sneak attack die for multiclassing.
Consider an Elf Rogue and get the Elven Accuracy feat. Whenever you have advantage you can take one of the two dice - the lowest one, I'd assume, and reroll it. Basically, it's like spending a luck point for an attack whenever you have advantage - so you get 3 chances for a crit instead of 2. Which, with tides of chaos, spells or shadow teleports can be very often, maybe every turn.
Mobile Feat + Assassin. If you go first, you get advantage, if the enemy is surprised you get auto-crit and the mobile is a bonus to your initiative and means you can slip away without provoking attacks of opportunity. Literally it's auto-crit attack, move, bonus action dash and you're usually safe from the enemy if they're melee fighters, if you're a shadow you could bamf back, if dim light/darkness, and attack with advantage and sneak attack again.
Luck feat. This probably does not need to be explained.
These are some ways to ramp up advantage and increase critical hit potential without needing a subclass. So take a look at these and other ways and think of a subclass that could better synergise with these for getting what you want and then consider things like 19-20 crit window, extra crit damage (like adding an extra 1d6). That's going to be the best way forward at adding the mechanics and keeping them balanced.
However, good mechanics will only go so far the rest will go into the story thematic - how can they RP this subclass? That is what gives those mechanics genuine intrigue and make people want to use it. Only you know the story concept so other than these paltry suggestions we otherwise cannot help you because the thing we most need from you to help more is the thing you are refusing to give. So please do not be upset or impatient with us if we cannot answer this in the way you would like: you're basically asking us to make a sandwich without bread, we're missing the vital part so our attempts will be basic and possibly not helpful.
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I agree completely with your closing arguments, I also would like to help OP make something fun and functional.
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"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
We can't really suggest uses for your charges without knowing the story. You're suggesting magical abilities but haven't explained what's the source of this Rogue's magic or why critical hits provide charges.
The largest hurdle you will have to clear is that of getting no charges. There is a decent chance you could go multiple play sessions without seeing a crit, even with an increased crit range involved. You don't see much in the way of 'charge up' mechanics in any classes because they are unreliable. Unreliable is incredibly frustrating when you are waiting for something special to trigger and then potentially have it happen in a low importance fight. Party takes a rest and there goes the charge.
War Magic's Power Surge is like that; however the subclass doesn't rely on Power Surge's availability; it's just icing on the cake.
The reliability issue is easily solved with a feature that gives you 1 charge if you roll initiative with no charges left. Several classes and subclasses have a feature like this (e.g. Bards, Monks, Arcane Archers, Battle Masters, Samurai.)
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The point of this point is to discuss the idea of having a resource that is based on landing critical hits. I have a story concept for it in mind, but will not be discussing it in this thread at the moment.
I wanted to pick the minds of people who have created things for D&D before, as I never have before. With the obvious issues of people trying to abuse the Luck feat, the Halfling racial trait that rerolls 1s, and multi-classing to give yourself better chances at critical hits put aside, what do you think about a subclass for the rogue that gains a resource to perform abilities when they land a critical hit.
The flavor of the subclass is to be hyper nimble, the maneuvers they can perform are hyper agile and some of them rely on the dexterity modifier or use it in some way. As such, they are restricted to finesse weapons and are not allowed to wear heavy armor to perform the maneuvers. That may be too restrictive for D&D, but I'm just spit-balling at the moment.
The bare-bones idea i have is the rogue can gain this resource whenever they roll a critical hit against an enemy. This resource they gain is capped at 5 charges and can be spent (1 at a time or multiple at once) to perform a special maneuver that gives the character's attack a little more oomph. For example, you can spend one charge to blink behind an enemy and if the enemy fails a perception check you get advantage on your attack roll against them. This would only be usable once per turn (in the event you multi-class to get multiple attacks per turn or action surges)
I know rolling a 20 on an attack roll doesn't happen all that often, but the subclass will grant abilities to slightly increase the crit window (similar to how the Champion archetype can get 19-20 or the Hexblade's Curse gives the 19-20 crit window as well), and toying with the idea that the subclass can gain a charge if they deal the killing blow to a target. Though, one downside to that is i can see some players worrying about kill stealing.
In my mind, the class is purely physical, they don't get any spell casting abilities, but some of their maneuvers allow them to perform some spell-like abilities (Like a modified Misty step for 1 charge in the ability described above or a modified Steel Wind Strike if they use all 5 charges at once.)
The charges can be retained after a battle and carried into the next one, but the player would lose half of their accumulated charges (rounded down) on a short rest and all of them after a long rest. I don't know of any out-of-combat abilities yet the charges could be used for, but I'm still in the early stages of this idea.
Now I understand this subclass wouldn't be viable for all games. At first glance it appears to be geared more for a combat-heavy campaign. However, this is a game where you can play any race/class/etc however you want, so there could be a place for it.
As i said at the beginning of the post, I'm temporarily ignoring the idea of multi-classing to make things a bit simpler at the beginning. After I get this idea nailed down, I'd start looking into how multi-classing can break this.
The ideas you have sound fine but you're still missing the most important details. If there's one thing the 5e designers have learned throughout the playtesting process is that the most successful subclasses are the ones that have a story that resonates with people and mechanics that tie into that story. There's already plenty of official and unofficial subclasses with interesting mechanics; you have to convince me to want to create a character with yours.
Start thinking about why this subclass exists. What's their place in the D&D world? Is this fighting style old or new? Regional? Invented by a specific race?
Also, you have to give it some non-combat features. Combat's just 1/3 of the game and no one class or subclass leans 100% towards combat, interaction or exploration. If you think it "wouldn't be viable for all games" you need to rethink your approach. Turn to existing Rogue and Fighter subclasses for inspiration.
You probably want to give the subclass at least one feature that gives it reliable combat utility; you could go an entire combat without seeing a critical hit. It doesn't have to be as strong as the tricks it can do on a crit, but without something else to rely on it's too hit-or-miss. Compare to Assassins: they get a huge buff if they get surprise (unreliable, might not happen on any given session) but still have a smaller more reliable benefit any time they beat their opponent's initiative. And despite being known for Assassinate, they get strong interaction/exploration abilities too.
The Forum Infestation (TM)
So... thief? The thief subclass is modeled after the original thief-acrobat of D&D, and they're all about using their Cunning action to do agile, hyper-nimble actions, tumbling around the battlefield. Sounds like you are just hard coding different tricks into concrete mechanics. As for finesse and armor... isn't that the rogue in general already?
I feel like you're just suggesting things that the rogue can already do, but unreliably with the crit-hit mechanic.
Maybe I failed to word it properly, but the post was meant to focus on the charges as a resource more so than the whole subclass. I am thinking of out of combat utilities for the subclass and have a story in mind, but just picking peoples minds on how the resource would work. I understand and agree with everything you mentioned though, so thank you for your comments.
I don't agree with the comparison to thief. The resources, when spent, mostly enhance the attacks the player can do, similar to how a gunslinger or a battle master can spend a grit/superiority die to do something. The only difference is they have to earn their charges, which allows for a stronger effect when the charges are used.
In comparison, a Thief is allowed to use their cunning action to perform a sleight of hand check to disarm traps or open doors, they're given the ability to jump further and climb without using extra movement, they can effectively cut their movement in half for advantage on stealth checks, they can use magic items that aren't meant for them. The only thing Thieves have that I can see clashing with the "hyper nimble" I suggested is they get to have 2 turns per round after level 17.
Again, maybe I worded my initial post poorly. Perhaps I should've said hyper nimble in combat or something.
In response to the finesse weapons and heavy armor restriction:
I rarely go out of my way to say something like this. But the idea sounds just plain bad, like some awful hybrid between World of Warcraft Rogues and Diablo 2 Assassin classes. You should figure out the story concept of the character before the mechanics, or you are doomed to a very sad result.
"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
Thanks for your opinion, but there's a better way to say this. I have a story concept in mind, I wasn't making this thread to 100% flesh out the character. I wanted opinions on using a resource mechanic based on landing critical hits.
Cunning Action... not being nimble? I've seen rogues tumble past enemies, backstab them, before running up a wall and perching there like a spider. Being nimble is pretty much the defining definition of about half the basic rogue's abilities. Maybe we're having an issue with the definition of the word nimble.
So, lets start with this. Forget describing the class in general. Start with describing your charges and exactly what it would allow. Don't just say teleport - there's already several ways to do so. Lets start with details. What are you trying to do besides critical hits and something teleporty?
You do remember that Cunning Action is a rogue trait, not specific to any one subclass, right? I was saying the claim that what I was suggesting was basically the Theif subclass reworked was not accurate. I never said anything about Cunning Action itself.
If you read my original post completely:
An example for another use could be to spend all 5 charges at once to gain the ability to pick X number of targets equal to your dexterity modifier within a range. The charges spent allow you to quickly move between these targets, making attack rolls against each of them and on success dealing a proportionate amount of damage. (I am aware there is a 5th level spell (Steel Wind Strike) that accomplishes this same effect, though the damage of the charged attack will not be the same as the spell). The tradeoff is the act of doing so causes a great deal of strain on the body and the player has to make a CON save or their speed is reduced to 0 for the following turn. The effects of using these charges could be modified as abilities in higher levels of the subclass.
I'm still in the early stages of this idea, so I don't have a whole slew of ideas prepared for what frenzy charges can be used for, however a possible minimum use and maximum use example have been provided.
Obviously none of this is set in stone and a good amount of thought still has to go into what the damage numbers would be.
The largest hurdle you will have to clear is that of getting no charges. There is a decent chance you could go multiple play sessions without seeing a crit, even with an increased crit range involved. You don't see much in the way of 'charge up' mechanics in any classes because they are unreliable. Unreliable is incredibly frustrating when you are waiting for something special to trigger and then potentially have it happen in a low importance fight. Party takes a rest and there goes the charge.
Suggestions on functionality would be to avoid the 'Nova effect' such as using all of the charges in one go for massive damage. Set caps on how many can be used in a turn dependant on level perhaps similar to the monk way of the four elements. Have some reliable way to get some charges, ie always have a single charge after a long rest, sacrifice a HD for a charge after taking damage. Try to avoid to strictly relying on the whims of fate to make the class features function.
"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
6 levels of Shadow Monk - when in dim light or darkness you can teleport 60 feet to another area in dim light or darkness and gain advantage on the next attack. This is a bonus action and costs nothing so basically meaning during a dungeon crawl or night-time you're guaranteeing a sneak attack on every turn.
If you take a 1 level dip into Sorcerer - Wild Magic you get "tides of chaos" which lets you give yourself advantage on an attack roll, ability check or saving throw. Once used takes long rest to recharge but it can also be recharged by using a spell of 1st level of higher - you immediately roll on wild surge table for a random effect that can be horrible, good, inconvenient or humorous. Spells to consider are Colour Spray (blinds enemies for a round, blinded enemies grant advantage to all attacks against them) and I definitely recommend Sleep spell. If you put the target to sleep, your next attack if they've not been woken up by somebody else, will not only be with advantage but, melee attacks on sleeping people count as auto-crits. If you take 3 levels you can have Quicken Spell metamagic and take 2nd-level spell Hold Person.Quicken Spell will let you cast your sleep/hold as a bonus so you can still attack right away with your action. Hold Person paralyses the target granting advantage to hit and if you hit in melee it's an auto-crit.
Consider 2 levels of Ranger. You get a fighting style and for a rogue I'd recommend Archer only if you rely on ranged attacks otherwise pick Dueling for the +2 damage. Rogue's are skirmishers and not much use relying on your AC, the idea is get in hit and get away. Only consider boosts to AC if you're a swashbuckler subclass which would not be the best choice for your intended build. You also get ranger spellcasting. You get 2 spell slots and can choose Zephyr Strike which is actually brutal when wielded by a Rogue. It's a bonus action so no loss of attacks, lasts a minute during which time your movement doesn't risk opportunity attacks which is great for rogues plus once during that minute, you can give yourself advantage on an attack which, if it hits, deals extra 1d8 damage and you can then move 30 ft, even if you miss. You can use the spell twice since you get 2 spell slots. Another good spell is hunter's mark for the extra 1d6 damage which is useful because if you do crit it gets rolled twice too. Also a good way to make up for possibly losing a sneak attack die for multiclassing.
Consider an Elf Rogue and get the Elven Accuracy feat. Whenever you have advantage you can take one of the two dice - the lowest one, I'd assume, and reroll it. Basically, it's like spending a luck point for an attack whenever you have advantage - so you get 3 chances for a crit instead of 2. Which, with tides of chaos, spells or shadow teleports can be very often, maybe every turn.
Mobile Feat + Assassin. If you go first, you get advantage, if the enemy is surprised you get auto-crit and the mobile is a bonus to your initiative and means you can slip away without provoking attacks of opportunity. Literally it's auto-crit attack, move, bonus action dash and you're usually safe from the enemy if they're melee fighters, if you're a shadow you could bamf back, if dim light/darkness, and attack with advantage and sneak attack again.
Luck feat. This probably does not need to be explained.
These are some ways to ramp up advantage and increase critical hit potential without needing a subclass. So take a look at these and other ways and think of a subclass that could better synergise with these for getting what you want and then consider things like 19-20 crit window, extra crit damage (like adding an extra 1d6). That's going to be the best way forward at adding the mechanics and keeping them balanced.
However, good mechanics will only go so far the rest will go into the story thematic - how can they RP this subclass? That is what gives those mechanics genuine intrigue and make people want to use it. Only you know the story concept so other than these paltry suggestions we otherwise cannot help you because the thing we most need from you to help more is the thing you are refusing to give. So please do not be upset or impatient with us if we cannot answer this in the way you would like: you're basically asking us to make a sandwich without bread, we're missing the vital part so our attempts will be basic and possibly not helpful.
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I agree completely with your closing arguments, I also would like to help OP make something fun and functional.
"Where words fail, swords prevail. Where blood is spilled, my cup is filled" -Cartaphilus
"I have found the answer to the meaning of life. You ask me what the answer is? You already know what the answer to life is. You fear it more than the strike of a viper, the ravages of disease, the ire of a lover. The answer is always death. But death is a gentle mistress with a sweet embrace, and you owe her a debt of restitution. Life is not a gift, it is a loan."
War Magic's Power Surge is like that; however the subclass doesn't rely on Power Surge's availability; it's just icing on the cake.
The reliability issue is easily solved with a feature that gives you 1 charge if you roll initiative with no charges left. Several classes and subclasses have a feature like this (e.g. Bards, Monks, Arcane Archers, Battle Masters, Samurai.)
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