you may regain a spell slot at any time. to do so deal to yourself necrotic damage equal to the spell slots level amount of d10s plus the spells level multiplied by your level

for example: to regain a first level spell slot at level one, you are dealt 1d10+1 necrotic damage. to regain a ninth level spell slot at 20th level you are dealt 9d10+180 necrotic damage.

let me know what you think. any changes? good? would you use these rules? players. what do you think? would you enjoy being able to regain spell slots in exchange for health?

I think this would only work if you bumped up the HP gained per level.  So for a Wizard with 14CON, and eventually getting that to 17 through a +2INT/+1Con ability score bump , you'd have an average of 140hp.  Just the base damage needed to be taken in order to regain a 9th level spell at 20th character level, you'd be at -40 HP and dead before you could even use the spell slot.  Even going with max HP for a wizard with the same 17Con, you'd only just make it to the 180 make and that's not counting the 9D10 you'd need to roll.  Even if someone was lucky enough to roll below average on all 9 dice, that's still likely at least 18 more damage and they're again dead and more than likley we're talking about average damage more than double that amount for the rolls.

As is, this rule would probably only help a Con caster like DND3.5/PF had with the Kineticist or if you were to change the Warlock and Sorcerer to be Con casters.  I do think the general idea of risking your life (hp) to gain back a desperately needed spell slot would have some interesting RP potential.  Maybe if they did take too much damage from gaining the spell slot back, it didn't get triggered until the end of their turn.  That would up the RP value a LOT.  That leads me to my next question.

When you say at any time, are we talking about at will, regardless of where the caster is at in the initiative turn or only turning their turn?  I ask because I'd limit it to once per round and only during their turn as a bonus action.  This would make the previous idea of the damage not triggering until the end of their turn make more sense.

Quote from Razzec >>

I think this would only work if you bumped up the HP gained per level.  So for a Wizard with 14CON, and eventually getting that to 17 through a +2INT/+1Con ability score bump , you'd have an average of 140hp.  Just the base damage needed to be taken in order to regain a 9th level spell at 20th character level, you'd be at -40 HP and dead before you could even use the spell slot. 

Conversely it also makes Death Ward one of he best spells ever. Cast a 4th level spell slot, gain a 9th level spell slot while at 1hp. For other spells, team up with a cleric to cast healing word on you after regaining the spell slot.

But I do agree with the overall point that the damage feels a bit high if it's intended be a feature that's regularly used. And I also don't think it makes sense to scale part of the damage on character level.

A 1st level spell slot being 1d10+1 damage at level 1 and 1d10+20 damage at lv20 doesn't make much sense IMO. Why would the higher level caster have a tougher time regaining the spell slot?

And the amount of damage does have the issue of pretty much killing you most of the time like you pointed out. At level 1 you're doing an average of 7 damage to your 8/9hp caster.

Quote from Razzec >>

I think this would only work if you bumped up the HP gained per level.  So for a Wizard with 14CON, and eventually getting that to 17 through a +2INT/+1Con ability score bump , you'd have an average of 140hp.  Just the base damage needed to be taken in order to regain a 9th level spell at 20th character level, you'd be at -40 HP and dead before you could even use the spell slot.  Even going with max HP for a wizard with the same 17Con, you'd only just make it to the 180 make and that's not counting the 9D10 you'd need to roll.  Even if someone was lucky enough to roll below average on all 9 dice, that's still likely at least 18 more damage and they're again dead and more than likley we're talking about average damage more than double that amount for the rolls.

As is, this rule would probably only help a Con caster like DND3.5/PF had with the Kineticist or if you were to change the Warlock and Sorcerer to be Con casters.  I do think the general idea of risking your life (hp) to gain back a desperately needed spell slot would have some interesting RP potential.  Maybe if they did take too much damage from gaining the spell slot back, it didn't get triggered until the end of their turn.  That would up the RP value a LOT.  That leads me to my next question.

When you say at any time, are we talking about at will, regardless of where the caster is at in the initiative turn or only turning their turn?  I ask because I'd limit it to once per round and only during their turn as a bonus action.  This would make the previous idea of the damage not triggering until the end of their turn make more sense.

 okay i think your suggestion makes sense. what if the damaged dropped to just the spell level d10s? do you think that would be enough for damage?

on your question: i was thinking that they gained the spell slot, but had to immediatly cast it. like it was basically they just used some of their life energy to cast a spell, not actually gaining any spell slot back. make sense? but it would only be on their turn. that i should have added.

Lower to d10 and immediate casting opens up an interesting interaction with cure wounds (particularly Life Cleric.) Take 6 damage and restore 11. A unique way to heal up. (Assumes +3 WIS modifier.)

Quote from VitusW >>

Lower to d10 and immediate casting opens up an interesting interaction with cure wounds (particularly Life Cleric.) Take 6 damage and restore 11. A unique way to heal up. (Assumes +3 WIS modifier.)

 thats fair.
*sigh*
ive always wanted to see something like this in dnd. but ive never seen it be possible. it sounds like a lot of roleplay fun, "(characters) eyes slowly fade as his fireball blasts off from his hand, he stumbles back feeling the shock of using that much energy" fun right? its so hard to think of the rule though. should i give up? or keep trying?