I am very sure that most aspects of this subclass are overturned; that being said, I am satisfied with the overall theme and basic premise of each feature. It is "what if Freddy Krueger was a subclass".
Some things I am already considering:
The level 14 feature that gets around Frightened immunity, I am going to change that to having normally immune creatures having advantage on the save still. I was considering having some form of resource cost to impose Disadvantage (or normal roll), but I don't know what the resource could be beyond using an extra pact slot.
The extra damage of Nightmare Terrain could be once per turn, but it is also balanced by positioning and having Dire Form active already, so I am split on whether it ought to stay as is or not.
The free casting of Fear and the available bonus action cast was really to free up action economy and costs, but I am aware that this is probably excessive.
The subtle casting of Illusion spells I am basing off of how GOO handles it; I figured including material components in exhange for limiting it to one school of magic was a fair trade, but I am aware as to what this does allow.
And I am sure other portions are a bit much. I just went with a theme and wrote stuff to help achieve it.
Any suggestions are helpful, because I do want this to be table ready.
Nightmare Terrain. You gain the ability to modify the Hallucinatory Terrain spell. You can choose to cast it as a Magic action; if you do, the duration is 1 minute and the area of effect becomes a 60ft cube.
Any creature of your choice within Hallucinatory Terrain (modified or not) must spend 4 feet of movement for every 1 foot it moves, and they take an extra 1d8 of damage when you hit them with your Unarmed Strikes while you are in Dire Form. The damage type is the same as the damage type used for the Unarmed Strike.
This is completely OP / Broken, it also doesn't make any sense. Creatures within Hallucinatory Terrain typically have figured out that it is an illusion so aren't really affected by it any more.
Also immunities exist for a reason, any ability that erases immunity is certainly broken. This is why WotC never builds classes / subclasses entirely around a single condition, or damage type (except force).
Dire Form : at low levels the AC is too high (AC at 3rd level should be ~16), it's unclear how it interacts with equipment like a shield or magic items like a cloak of protection. Meanwhile the damage is not good, the character would most of the time be better off using Eldritch Blast + Agonizing Blast.
Lastly, this subclass does not work well with many core Warlock features, e.g. Pact of the Blade : useless, Eldritch Blast: useless, Hex : mostly incompatible. In addition, most of your stipulations about "any warlock spell that causes fear" are mostly useless since there are only 4 spells on the Warlock spell list that cause fear : Cause Fear (1st level and very bad spell), Fear (3rd level), Eye Bite (6th level requires spending limited Arcanums to get it), Weird (9th level and very bad spell). Why is this a Warlock subclass?
IMO this subclass would make much more sense as a Druid subclass, they already have a shapechanging ability which you can augment with the "Dire form" option, they also get much more in the way of terrain modification spells which would work much better than Hallucinatory Terrain for that thematic thread.
Alternatively, Monk would provide appropriately scaling melee-attacks which you could modify in the subclass to have different damage type options similar to Elements Monk, and allow it to create illusions with Focus Point similar to the pseudo-fire ball the Sun Soul Monk can use.
Or if you are committed to a CHA-based character Paladin would be a better option, again melee attack scaling is built right in as well as melee-survivability, and you have a resource to use for the transformation (CD). Plus, Wrathful Smite would really work well with this subclass.
Just looking for critique and suggestions to iron out and reign in a subclass I have published here.
https://www.dndbeyond.com/subclasses/2579874-fearmonger-patron
I am very sure that most aspects of this subclass are overturned; that being said, I am satisfied with the overall theme and basic premise of each feature. It is "what if Freddy Krueger was a subclass".
Some things I am already considering:
The level 14 feature that gets around Frightened immunity, I am going to change that to having normally immune creatures having advantage on the save still. I was considering having some form of resource cost to impose Disadvantage (or normal roll), but I don't know what the resource could be beyond using an extra pact slot.
The extra damage of Nightmare Terrain could be once per turn, but it is also balanced by positioning and having Dire Form active already, so I am split on whether it ought to stay as is or not.
The free casting of Fear and the available bonus action cast was really to free up action economy and costs, but I am aware that this is probably excessive.
The subtle casting of Illusion spells I am basing off of how GOO handles it; I figured including material components in exhange for limiting it to one school of magic was a fair trade, but I am aware as to what this does allow.
And I am sure other portions are a bit much. I just went with a theme and wrote stuff to help achieve it.
Any suggestions are helpful, because I do want this to be table ready.
This is completely OP / Broken, it also doesn't make any sense. Creatures within Hallucinatory Terrain typically have figured out that it is an illusion so aren't really affected by it any more.
Also immunities exist for a reason, any ability that erases immunity is certainly broken. This is why WotC never builds classes / subclasses entirely around a single condition, or damage type (except force).
Dire Form : at low levels the AC is too high (AC at 3rd level should be ~16), it's unclear how it interacts with equipment like a shield or magic items like a cloak of protection. Meanwhile the damage is not good, the character would most of the time be better off using Eldritch Blast + Agonizing Blast.
Lastly, this subclass does not work well with many core Warlock features, e.g. Pact of the Blade : useless, Eldritch Blast: useless, Hex : mostly incompatible. In addition, most of your stipulations about "any warlock spell that causes fear" are mostly useless since there are only 4 spells on the Warlock spell list that cause fear : Cause Fear (1st level and very bad spell), Fear (3rd level), Eye Bite (6th level requires spending limited Arcanums to get it), Weird (9th level and very bad spell). Why is this a Warlock subclass?
IMO this subclass would make much more sense as a Druid subclass, they already have a shapechanging ability which you can augment with the "Dire form" option, they also get much more in the way of terrain modification spells which would work much better than Hallucinatory Terrain for that thematic thread.
Alternatively, Monk would provide appropriately scaling melee-attacks which you could modify in the subclass to have different damage type options similar to Elements Monk, and allow it to create illusions with Focus Point similar to the pseudo-fire ball the Sun Soul Monk can use.
Or if you are committed to a CHA-based character Paladin would be a better option, again melee attack scaling is built right in as well as melee-survivability, and you have a resource to use for the transformation (CD). Plus, Wrathful Smite would really work well with this subclass.