So had a read threw as I am creating a Divine soul sorcerer with Ritual casting feat, Find familiar will be raven as i just do not like Owl.

It's main use is going to be rapid delivery of cure wounds or spare the dying so my sorcerer can stay well away from trouble. A kind of Air ambulance. that leaves my sorcerer open for better meta magic saves taking distant spell and who doesn't want a free pet.

I'm going to have a cat or raven familiar for my wizard, and that's entirely for flavor reasons. She's modeled after gothic heroines of the Brontëan tradition, and what's more gothic than wandering the moors with a black raven flying overhead, or sitting in a mouldering country manor with a black cat in your lap?

Although as a concession to optimization, I'll probably go with a raven so I can warg into it while it's flying, for reconnaissance purposes.

Quote from DungeonLord58 >>

In a campaign, my DM allowed my Great Old One warlock to have a gazer for a familiar.

 Wow ... social implication? :)

Just happy my DM agreed to a Wolf familiar. Just love dogs, love the visual and dipping into Ranger would have been silly just for that.

Just Saying my owl Famiar Named Mr Handy (Nicknamed B-17 StratoFortress) was SUPER useful for dropping alchemists fire and molatov cocktails on the enemy

I have a gazer currently. Not one you can summon, I know, but my party found him in a dead Beholder's lair. His name is Hector and he likes slamming things into walls. Useful little ball of hatred when you need help, plus, seeing through his eyes is very useful for scouting ahead, Hector is a bit of a whistle blower for them there sneaky goblins and such.

I created a Mage Hunter Wizard. He is from Chult, so I picked a Tarantula for his familiar. It works great with the overall idea of the build. Since he hunts down evil mages and necromancers, having the tarantula be able to be sent out for recon and peek around corners will be very important.

This is meta gaming, but I’m so tempted to have a bat familiar and cast either darkness or fog cloud all of the time and have the familiar tell me where to target my area of effect spells. That won’t work for spells that require an attack roll, but it will for fireball and the like. 

That is just using the tools given to you, only downside is catching your teammates in the darkness.  Unless they are a warlock.

My group house-ruled it so that any tiny creature with a CR of 1 or less can be your familiar, that way a necromancer can get a crawling claw. I'm also a fan of letting high-level casters get more powerful familiars. When a Player hits 17th level, having a pet flameskull isn't going to break the game any more than they already can by that point.

Quote from Cthulu3141 >>

My group house-ruled it so that any tiny creature with a CR of 1 or less can be your familiar, that way a necromancer can get a crawling claw. I'm also a fan of letting high-level casters get more powerful familiars. When a Player hits 17th level, having a pet flameskull isn't going to break the game any more than they already can by that point.

 Did you mean to say CR:0?
Because the Crawling Claw is CR:0 as is every other familiar from Find Familiar.

I'd understand any Tiny creature of CR:1 for less if you're a Warlock.

I'm still curious why cats don't have Dark Vision but owls do? Cats are capable nocturnal hunters. I can understand why they wouldn't get 120 ft. vision but 60 would make sense.

Another curiosity is an owl's hp. It's 1d4 - 1. What if you roll a 1? I assume it doesn't start with 0 hp and immediately die?

Quote from Emmote >>

I'm still curious why cats don't have Dark Vision but owls do? Cats are capable nocturnal hunters. I can understand why they wouldn't get 120 ft. vision but 60 would make sense.

Another curiosity is an owl's hp. It's 1d4 - 1. What if you roll a 1? I assume it doesn't start with 0 hp and immediately die?

 with hit points you always get a minimum of one, just like when you roll dice for hp on a level up, you always get at least one.

Yeah I agree cats should get something like darkvision, but I like the idea of them having true vision at a short range.  Cats being halfway into the other realm anyways right?  Like when a cat walks up to someone in a friendly manner and then they get a look at them and go OH HECK NO and run away.

Actually, you can get 0, or even negative hit points for levelling up, if your Constitution bonus is negative.

Thus far I've been using a rat for multiple reasons. Most of the uses can be done with other forms but the darkvision helps with the rat.

One is with dragon breath i can use the touch portion of the spell to grab the rat while casting a bonus action spell and point him so he can use his action to activate the spell and I have an action to do what I want. It's less vulnerable to single target attacks since to hit it they basically have to hit me with my hand on the rat. i.e. I have a rat flame thrower, alternatively i can cast it when the rat is in position for an ambush and he uses his reaction to deliver the touch spell on himself and then his action to breath the spell.

Rats have a strong destructive capacity but also are flexible in tool manipulation. I've discussed it with my familiar and worked out with the GM that with practice my rat can apply a potion of healing on me when I fall unconscious since I keep a small wineskin pouch around my neck.

If a rat appears suddenly people don't usually question it since rats are fairly furtive so I can go up to a door, dismiss the rat and have it appear on the other side to tell me what's there since the spell states that I can have the familiar reappear in an unoccupied space within 30' that can be on the other side of a door even if I can't see it. This is when darkvision tends to get helpful.

I've used it to provide LOS so if it's within 30' I can then use an action to swap vision modes then using bonus action misty step to its location or to a visible location 30' from my location that it can see but I can't. 

Rats resemble genetic and biological behavior which is part of why they're in clinical trials so my familiar is also my food taster.  It gets to eat first before I try anything. 

Rats are fairly innocuous so I can use it to set traps when planning an assault with the party. eg. casting snare (1 min) range touch using the rat to dart in, use its react to finalize the spell with touch, and its action to bamph into the pocket dimension or sneak about while I can several trap spells in enemy turf.  I plan on discussing it my GM and since if I cast the spell from a scroll, all the components would be consumed before hand therefore I don't necessarily have to have the rope on site so the rat could deliver snare at range. Optionally I've thought about inscribing a glyph on a rock, which the rat can carry to its destination and activated a glyph of warding once it arrived at it's location. 

Rats are excellent climbers and swimmers which make them flexible in multiple terrain types. If they can fit their head in, their bodies can collapse to follow. Ask any pest control technician. 

Keep in mind that traditionally familiars were summoned to assist in casting spells. So you could have it use its help action to help you focus a spell to gain advantage on a spell attack without flying into the face of the enemy with an owl. It's a fey spirit and more attuned to the nature of magic. 

Despite its inability to attack, sage advice considers familiars as allies and valid for sneak attack. So the rat can hitch along a companion for either sneak attack or pack tactics. 

Lastly it was because I decided I'd name it Chewie.

Jawls, you have some pretty creative uses for familiars, although only a few of those are specific to the rat familiar. I never thought about having the familiar appear on the other side of a door, although the wording of the spell doesn't say you can't do that. In particular, I like your idea of using your action to see through your familiar and then using your bonus action to misty step. That's great! I don't know if I'd allow a rat to feed a player a potion, but that is absolutely the prerogative of your DM so I'm not saying it's wrong.

If I read your penultimate paragraph correctly, you say you saw a Sage Advice referring to a familiar traveling in your own square on your person acting as an ally threatening a target to give sneak attack. Would that require the familiar to use the help action? Can you link me to that please? I'm curious about the wording of the question and the answer.

Quote from Emmote >>

I'm still curious why cats don't have Dark Vision but owls do? Cats are capable nocturnal hunters. I can understand why they wouldn't get 120 ft. vision but 60 would make sense.

Another curiosity is an owl's hp. It's 1d4 - 1. What if you roll a 1? I assume it doesn't start with 0 hp and immediately die?

 
You can choose not to roll and start with the average which is given in the state block and this is usually recommended if you have a negative con mod. The hit die roll is given for when you wish to regain hit points by spending hit die during a short rest, which can never roll below 0. So, 1d4-1 is an average of 2. Your familiar can start with 2 HP and if got damaged for 1 HP it can roll its hit die on a short rest so you roll the 1d4-1. Any score below 0 is treated as a 0. So, you have equal chance of getting a 0, 1, 2 or 3 and healing this amount, up to your maximum of 2 HP. It's not likely this will ever happen, but it might.

The same applies to player characters: while Tonio is correct if you "level up" you can actually get negative results and these detract from your maximum HP. But, you have the option to take average instead of rolling so if you were a wizard (d6) and rolled the lowest score for your con: 3, this is a -4 mod so you won't get any new health but you will not lose any either and on your next ASI bump your CON by 2 and suddenly you're getting 1 health each level up by taking average - and future Con bumps and Tough feats can help keep your health at the lowest edge of acceptable. Using hit dice on level up is different to using hit dice on short rests for healing. On short rests you cannot take average but any roll below 0 is considered a 0.

Why am I mentioning about character hit dice? Because the rules on hit dice usage applies to all creatures, not just PCs. When a DM chooses to use a monster they can roll their health or take average, just like you can for your characters and, for your familiars.

Quote from Cyb3rM1nd >>

Quote from Emmote >>

I'm still curious why cats don't have Dark Vision but owls do? Cats are capable nocturnal hunters. I can understand why they wouldn't get 120 ft. vision but 60 would make sense.

Another curiosity is an owl's hp. It's 1d4 - 1. What if you roll a 1? I assume it doesn't start with 0 hp and immediately die?

 
You can choose not to roll and start with the average which is given in the state block and this is usually recommended if you have a negative con mod.

 Yea I understand that you can choose not to roll. The owl stat block says it's HP is 1 normally. But if you do choose to roll and you rolled a 1 what would you say the result is? An owl with 0 max HP and you'd need to cast again or just say the minimum is 1?

Quote from TexasDevin >>

If I read your penultimate paragraph correctly, you say you saw a Sage Advice referring to a familiar traveling in your own square on your person acting as an ally threatening a target to give sneak attack. Would that require the familiar to use the help action? Can you link me to that please? I'm curious about the wording of the question and the answer.

This sage advice is the best I've been able to find on the matter.
https://www.sageadvice.eu/2015/12/02/two-familiar-questions/

Quote from Emmote >>

Quote from Cyb3rM1nd >>

Quote from Emmote >>

I'm still curious why cats don't have Dark Vision but owls do? Cats are capable nocturnal hunters. I can understand why they wouldn't get 120 ft. vision but 60 would make sense.

Another curiosity is an owl's hp. It's 1d4 - 1. What if you roll a 1? I assume it doesn't start with 0 hp and immediately die?

 
You can choose not to roll and start with the average which is given in the state block and this is usually recommended if you have a negative con mod.

 Yeah, I understand that you can choose not to roll. The owl stat block says it's HP is 1 normally. But if you do choose to roll, and you rolled a 1, what would you say the result is? An owl with 0 max HP and you'd need to cast again, or just say the minimum is 1?

 
I don't have an answer in any kind of "official" capacity but in all the games I have played, the rule is if you roll and get 0 or less your familiar will get 1 HP. I think Matt Mercer applies the same rule on Critical Role for Caleb's familiar if I remember correctly. In my game and the ones I am currently playing we have a houserule also about levelling up with hit dice in that you always roll the hit dice and take either the roll or average whichever is higher - but the same is applied to monsters for their health too for any monsters with class levels or NPCs made the same way as a PC (barring any story/balancing needs to adjust their HP more manually, yay DM powers - in my game some of the most powerful creatures are vampires and dragons - there is no rolling, they get Max HP but I also try to ensure this is reflected in the encounter difficulty). None of of the player characters in my campaign in which I am DM have familiars and if they ever do I will be making a house rule that familiars start with the maximum HP instead of rolling. It is a little bit more helpful and nicer for the players but at the same time has absolutely no effect on balance because familiars are extremely low CR creatures.

Im an evoker who chose raven because, a) I thought it was cool and b) It has good perception and mimicry is so useful.

Quote from Jawls >>

Thus far I've been using a rat for multiple reasons. Most of the uses can be done with other forms but the darkvision helps with the rat.

One is with dragon breath i can use the touch portion of the spell to grab the rat while casting a bonus action spell and point him so he can use his action to activate the spell and I have an action to do what I want. It's less vulnerable to single target attacks since to hit it they basically have to hit me with my hand on the rat. i.e. I have a rat flame thrower, alternatively i can cast it when the rat is in position for an ambush and he uses his reaction to deliver the touch spell on himself and then his action to breath the spell.

 

 

Despite its inability to attack, sage advice considers familiars as allies and valid for sneak attack. So the rat can hitch along a companion for either sneak attack or pack tactics. 

 A) SIgh rats have darkvision and cats don't? whyyyyyyyy? :)

B) I thought if you used a Familiar to attack by using Dragon Breath it counted as the Casters Action ergo only had Reaction and Bonus Action left in his turn?