Rule modification to find familiar

A Familiar's Feeling

When an attack would reduce you to 0 hit points, and your familiar can perceive the attacker, your familiar can use its reaction to attempt to interpose itself.

If your familiar is close enough to reach your space using its available movement, roll a d10.

- On a 10: Your familiar dashes to your position and absorbs the attack's damage in your place. You take no damage from a single-target attack. Your familiar's hit points are immediately reduced to 0, causing it to disappear. It must be summoned again as normal using the Find Familiar spell.

- On a 1–9: Your familiar fails to interpose itself, and the attack resolves normally. Your familiar retains its position and hit points.

Restrictions: This feature cannot be used against damage or effects your familiar cannot perceive, ongoing environmental damage, ongoing status effects, or damage caused by you.

Area-of-Effect Attacks: If the familiar successfully intervenes against an area-of-effect attack, you take half the damage you would otherwise receive, rounded down, and the familiar's hit points are reduced to 0. However, if the reduced damage would still reduce you to 0 hit points, the intervention fails entirely. The reaction is expended, but the familiar retains its hit points and position.

I wouldn't make an actual rule for this, and would never use it more than once. If you think it fits the story for someone's familiar to do this at a critical point in the campaign, go for it. But players shouldn't expect this to happen, and familiars aren't meant to be a free 'protect me from death card'. Too many people abuse the rules around familiars as is, why give them anotherr way to do it.

I think that's a great narrative way to allow a familiar to offer a little sliver of hope in a very tense moment. That being said, I wouldn't simply allow the familiar to tank all the damage for an attack, since familiars only have 1 or 2 hit points. If you're down to just a handful of hit points and a fire giant hits you with a flaming sword, there's no way a single-hit-point familiar could tank a hit that does an average of 31 hp of damage. Instead, I would rather allow the familiar to fly up into the enemy's face to distract it, thus imposing disadvantage on that attack roll. It's basically a reskin of the light cleric ability Warding Flare, but with extra steps. That way, maybe the attack misses and you survive. But if the attack hits, sorry, start rolling 4d6 and dropping the lowest. 

Thanks for the feedback, everyone! I probably didn't explain my idea clearly enough. I imagine the familiar physically pushing its master out of the way, sacrificing itself to save them. Against a single-target attack, you avoid the damage; against an AoE, you still get caught in the effect, which is why you take half damage.

I did consider adding a drawback, like being pushed one tile away or falling prone. However, being prone could make things worse, since nearby enemies would have advantage on their attacks against you. I wanted to keep the mechanic simple while making the familiar's sacrifice meaningful.

I understand the concerns about balance and familiars becoming a free way to avoid death. That's why I made success only a 10% chance. I'm exploring whether this could work as an optional rule, not claiming it's perfect as written.

Oh! Here's a thought.  I was initially concerned with balance issues. So I was thinking about how to balance a 1 hp familiar tanking a really big hit. But there is another way that I think would justify it.

When you cast Find Familiar you summon something that looks like a little beast, but it's not a beast. It's actually the spirit of a celestial, fey, or fiend in the form of a small beast.  That offers a great way to balance this! 

If the character is about to be hit and die, the familiar could either push the character away or interpose itself in the path of the attack. The familiar takes the hit and the character survives. BUT... whatever celestial, fey, or fiend sent that familiar to you has just done you a great favor. So now you owe them a great favor!  So the character lives to fight another day, but they'll have this thing hanging over their head every day, never knowing when the extra-planar being will show up to demand that favor, or even what form that will take.  And that could provide a fun way to introduce a little side-quest! 

Quote from AnzioFaro >>

Oh! Here's a thought.  I was initially concerned with balance issues. So I was thinking about how to balance a 1 hp familiar tanking a really big hit. But there is another way that I think would justify it.

When you cast Find Familiar you summon something that looks like a little beast, but it's not a beast. It's actually the spirit of a celestial, fey, or fiend in the form of a small beast.  That offers a great way to balance this! 

If the character is about to be hit and die, the familiar could either push the character away or interpose itself in the path of the attack. The familiar takes the hit and the character survives. BUT... whatever celestial, fey, or fiend sent that familiar to you has just done you a great favor. So now you owe them a great favor!  So the character lives to fight another day, but they'll have this thing hanging over their head every day, never knowing when the extra-planar being will show up to demand that favor, or even what form that will take.  And that could provide a fun way to introduce a little side-quest! 

 Again, why does this need to be a rule regarding Find Familiar... can't that Celestial, Fiend, or Fey just intervene on their own, and expect a favor in return? Why tie this to a familiar? Are you going to give a similar benefit to non-spellcasters or those who can't get the Find Familiar Spell?

It's not a rule. It's a suggestion.

And it regards the spell Find Familiar because that's the spell that Arm229 specifically asked about. 

These are just fun little narrative ideas that we're playing with here. Nothing is being taken away from anyone. 

This is just a fun little fantasy game that we play. We're just making up a fun little way for someone to have a special little moment in the game. None of these suggestions are binding at anyone's table. We're just having fun.

I’m aware this idea is half-baked and would need battle-testing, balancing, and probably some wording changes.

HarmAssasin, you bring up an interesting point: this could technically be applied to any creature, including player characters, but I wouldn’t recommend that. I chose familiars because losing one isn’t necessarily the end. They’re replaceable; if one dies, you can summon it again.

From a role-playing perspective, though, I want it to feel like a carpenter’s hammer. It’s a replaceable tool, but after years of use, it has molded to your hand. You know its weight, its balance, and its familiar feel. It’s been with you through all your ups and downs.

Now imagine that hammer had a soul. I’d like to think that, in your moment of greatest need, it would jump to save you—even if doing so meant it could never be a hammer again.