Damage removal “healing” cantrip

The DMG outright states that a cantrip shouldn't offer healing. The obvious problem with a healing cantrip is that the party could heal up after every encounter. But what if the cantrip was only usable during the fights, e.g. by requiring that the healed damage was dealt within the last round?

It feels that this could be balanced by considering that if a character spends their action healing, they are not dealing damage. Therefore, the monster dies slower, dealing more damage to the party. If the healing cancels that damage, we're even. For example, assume that a monster deals 10dmg/round and dies in 3 rounds if all 4 players hit it. With 3 players, it dies in 4 rounds, dealing an extra 10 damage. Spreading this over 5 castings (4 rounds + 1 extra after the combat ends), a cantrip that heals 2 sounds reasonable.

I run some numbers using the recommended HP/DMG by CR stats and having players dealing 1d10+4 (scaled at 5/11/17) and hit rates of 0.65 and 0.4 for the players and the monsters and it looks like the cantrip should heal 3.6hp, so 1d6 (scaled to 2d6/3d6/4d6 at 5/11/17). Something like:

Within one round after someone takes damage, you try to mend their wounds and revert up to 1d6 of damage (no more than the damage dealt). This is not considered a hit point restoring effect. Higher levels: prevent 2/3/4d6 at level 5/11/17.

At low levels it's balanced against Cure Wounds, which heals over twice as much, then it becomes obsolete (but so do damage dealing spells). Another possibility would be having a medicine check, possibly based on the monster's save DC and increase the healing a bit.

Does this sound reasonable? Am I missing something? Obviously fights will take (a bit) longer, but that's acceptable. I'm more concerned about the balance of the intended usage (during combat only, when spending an action to cast it is meaningful), as opposed to an exploit to gain unlimited healing.

• @GreySage I changed prevent to revert, it's meant to be cast after the damage is dealt. I want to avoid any synergies with abilities such as Supreme Healing (maximize rolls that restore hit points), hence the awkward phrasing; hope it makes sense now. – falsedot Nov 22 '19 at 22:45
• @jgn that's good answer as a reaction to damage puts a solid limit on it. you should right that up as an answer. – John Nov 23 '19 at 3:35
• As for your next version, @falsedot, I would recommend reviewing the feedback, doing some more thinking and potentially play testing and then submitting a revised homebrew after you've given some time and additional effort into the revision. – NautArch Nov 23 '19 at 19:59
• @NautArch makes sense, thanks! – falsedot Nov 24 '19 at 15:03

It's unbalanced

The difference between a concious and an unconcious ally during combat is huge. So much so that bringing a creature at 0 HP back to conciousness during combat is an unbalanced effect for a cantrip. Your cantrip can do so an indefinite number of times, which is especially problematic at low levels.

In addition to that big problem, there are at least two smaller problems.

This cantrip can turn temporary HP into normal HP through damage, which is an especially annoying because there are some sources of unlimited temporary HP in tha game.

Multiple casters with this same cantrip can, as a group, revert more damage than what was dealt during the last round.

Flawed design

The fundamental design flaw is that this cantrip works an indefinite amount of times, so small problems can balloon into nasty exploits. As a result, you are forced to include clunky clauses that burden the design.

The need to keep track the amount of damage each round for every creature is clunky. The fact that the cantrip is not considered to restore hit point is clunky. The clauses you will have to add to patch the problems I mentioned earlier will be clunky too.

If you were to limit how many times the cantrip works, none of those small problems would matter, but a cantrip that is not at-will is a cantrip in name only.

My original answer contained an exploit that no longer exist in the edited question (healing for more than damage dealt), so I am updating my answer to highlight other issues

Even if a single casting cannot heal more than the damage dealt, what about multiple castings?

Say the paladin takes 4 points of damage this round. Since the spell can only heal for the max amount of damage sustained in a round, two casters could each cast the cantrip for their max of 4hp giving the paladin 8hp back? Since "This is not considered a hit point restoring effect," how would the cantrip know the healing has already been done?

The argument of "but it takes an Action" is kind of moot.

Because ANY effort of healing within combat will take an action. Cure Wounds, Heal, Lay on Hands, drinking a potion. A kind DM might say that eating a Goodberry would be a Free Action, but that's more of an edge case.

But since all healing is going to take an Action, difference is this spell drops the "used resource" barrier; no spell slots used, no once-a-day feature, no limited supply of potions.

Also, saying it is meant to be "in combat only" is misleading

As people can remain "in combat" even after all the enemies are dead. Characters can still take turns; it's just generally accepted that once the enemy is no more, you stop.

• While the question was edited to make objection 1 more clearly obsolete, that edit predates your answer. Your third point is correct, however. – Please stop being evil Nov 22 '19 at 23:39
• yep, sorry about not being clear about #1 from the beginning. I think that points 2,3 are not really exploits; they are giving up actions to heal, hence prolonging the fight, hence taking more damage which evens out. Nevertheless, it would make sense that if the damage has been reverted, there no more damage for the 2nd player. – falsedot Nov 23 '19 at 0:01
• You've omitted the major exception of the bonus action spell Healing Word. It is such a go to option for low level healing that the OP may have been thinking of it as the standard. – Benjamin Olson Nov 23 '19 at 1:50
• Actually it does not seem like multiple castings on the same damage require multiple casters. The cantrip can be readied allowing the same caster to get out 2 of the casts in one round. – fabian Nov 23 '19 at 1:54

In general, access to infinite healing is very rare in D&D 5.0.

The problem of infinite healing is that it may trivialize encounters against low-level critters. Normally, a high-level fighter should still be afraid of a horde of 100 rats. Many rats will fail to hit, however little by little they may wear him down and even if he succeeds, force him to expand some resources.

With such a cantrip, however, a party of two: our high-level fighter and some sneaky -- or otherwise inaccessible -- henchman with the cantrip, can take on the rats. As long as the fighter suffers at most one hit per round, the cantrip will revert the damage.

Consider the fact that the Champion's capstone, at level 18, is infinite healing up to half its Hit Points maximum. From the SRD:

Survivor

At 18th level, you attain the pinnacle of resilience in battle. At the start of each of your turns, you regain hit points equal to 5 + your Constitution modifier if you have no more than half of your hit points left. You don't gain this benefit if you have 0 hit points.

Your cantrip is, in good hands, more powerful that this capstone: way too good.

• I think your scenario if the Fighter suffering only one damage per round is rather inconceivable. That means the combat would have to last over fifty rounds. Though I do understand the jist of the argument – Medix2 Nov 23 '19 at 19:29
• @Medix2: I hadn't realized the ambiguity of "less than", I meant <= obviously, I switched to "at most one" which should be clearer. I also cited the Survivor Champion capstone. – Matthieu M. Nov 23 '19 at 19:29
• @Medix2: Is it? A high-level Fighter should generally have a rather high AC. AC 21 is "just" Full Plate +3, and that's not accounting for a Fighter wearing a Shield, picking the Defense Fighting Style, or picking the Dual Wielder feat. On the other hand, a Rat has a +0 to attack and 1 attack per round. Even accounting for flanking rules, that's only 10% chance to hit each round (rolling a Nat. 20 with Advantage). Given that not all 100 Rats can be adjacent to the Fighter at a time -- especially if the Fighter finds a tree/wall to guard its back -- it's reasonable to expect avg. <= 1 hit/round. – Matthieu M. Nov 23 '19 at 19:34
• That probably came across less kindly than in my head. Your scenario makes sense to me now, thank you! – Medix2 Nov 23 '19 at 19:46

This would be the only spell able to bypass Chilling Touch (which shuts down all healing); I can't say I like that.

It also brings people up from 0, but since 0 is as low as HP goes, now you have a cantrip which restores people to fighting condition? Or not. because it only undoes damage? I am confused with how this would interact with a downed PC.