Does the necromancer's grim harvest work with summon undead?

[Throne12]

So does this work?

[Rfkannen]

I really want it to, but I think by raw no. You summon a creature, the creature does the killing. You aren't killing anything, so you don't get the health back.

[AvvyR]

In what way? Are you asking if you summon an undead, and it kills something, does that count as you killing it with a necromancy spell, therefore you should regain the HP from Grim Harvest?

If so, I'd say a creature summoned by a spell killing a creature doesn't count as the spell itself killing them, so no. This would not be a new phenomenon, as even in PHB only, undead created with Animate Dead fall into the same category.

[Thunderous Mojo]

No, the creature marshaled by Summon Undead is a medium sized undead.
It does qualify for Undead Thralls.

[MaxWilson]

So does this work?

I wouldn't let it work with Animate Dead because Animate Dead is instantaneous--by the time the creature kills anything, the spell is already over. (Ditto for Goodberry and Disciple of Life, doesn't work.)

However, Summon Undead's duration is 1 hour, so... maybe. I'd let Grim Harvest trigger off of Wall of Fire or Evard's Black Tentacles, is Summon Undead really any different? Then again, is Tiny Servant different from Summon Undead? I don't love the idea of letting Grim Harvest trigger off Tiny Servant, but I dislike the idea of not letting it trigger off of Wall of Fire or Bigby's Hand. What to do?

Let's review the text of Grim Harvest:

At 2nd level, you gain the ability to reap life energy from creatures you kill with your spells. Once per turn when you kill one or more creatures with a spell of 1st level or higher, you regain hit points equal to twice the spell's level, or three times its level if the spell belongs to the School of Necromancy. You don't gain this benefit for killing constructs or undead.

I guess I would let it work with Summon Undead, or Tiny Servant for that matter, since those creatures are created entirely by your magic. I don't think I would allow it with True Polymorph or Polymorph though, or Haste, since in that case the creature doing the killing is a pre-existing creature, not part of you or your magic.

I don't love this ruling but I think it's the best I can do with the rule as written. It certainly is a powerful ability under the right circumstances.

[MrCharlie]

I wouldn't let it work with Animate Dead because Animate Dead is instantaneous--by the time the creature kills anything, the spell is already over. (Ditto for Goodberry and Disciple of Life, doesn't work.)

However, Summon Undead's duration is 1 hour, so... maybe. I'd let Grim Harvest trigger off of Wall of Fire or Evard's Black Tentacles, is Summon Undead really any different? Then again, is Tiny Servant different from Summon Undead? I don't love the idea of letting Grim Harvest trigger off Tiny Servant, but I dislike the idea of not letting it trigger off of Wall of Fire or Bigby's Hand. What to do?

Let's review the text of Grim Harvest:

At 2nd level, you gain the ability to reap life energy from creatures you kill with your spells. Once per turn when you kill one or more creatures with a spell of 1st level or higher, you regain hit points equal to twice the spell's level, or three times its level if the spell belongs to the School of Necromancy. You don't gain this benefit for killing constructs or undead.

I guess I would let it work with Summon Undead, or Tiny Servant for that matter, since those creatures are created entirely by your magic. I don't think I would allow it with True Polymorph or Polymorph though, or Haste, since in that case the creature doing the killing is a pre-existing creature, not part of you or your magic.

I don't love this ruling but I think it's the best I can do with the rule as written. It certainly is a powerful ability under the right circumstances.
The question is if you are doing the killing, or if the summon is. To say nothing of if a spell being instantaneous means much at all, when it clearly has persistent effects past the duration-I remember there being a couple of other examples where the rules become strange around that distinction, though I don't remember what they are off the top of my head.

[MaxWilson]

The question is if you are doing the killing, or if the summon is. To say nothing of if a spell being instantaneous means much at all, when it clearly has persistent effects past the duration-I remember there being a couple of other examples where the rules become strange around that distinction, though I don't remember what they are off the top of my head.

Those same kinds of questions can arise with other spells, like Evard's Black Tentacles and Wall of Fire. Is it the necromancer doing the killing, or the tentacles? Is it the necromancer doing the killing, or the warlock who knocks somebody into the tentacles/fiery wall? I am inclined to rule those questions generously (treat Grim Harvest as applying to any damage coming from an active spell of the Necromancer's), and so I think I'd probably rule that way for things created from magic (Bigby's Hand, Mordenkainen's Sword, Spiritual Weapon, Summon Undead, Tiny Servant), although not to things summoned from elsewhere (Summon Greater Demon).

I could see it either way. Maybe I'd change my mind eventually and say "no if the things doing the damage is a creature with its own, separate actions and turns." I'd have to look at all the available spells and see what spells each ruling affects--there's no obvious place to draw the line.

[Monster Manuel]

I guess the metric I would be using is "does it exist apart from the spell that created it"? In cases where the spell creates a Thing, but then the Thing exists independent of the spell, I rule it that it is the Thing that causes effects to happen, not the spell. Say, a Wall of Stone which is created by a spell but after that point is just a stone wall. If it falls on someone and crushes them, it's the wall that did the damage, not the originating spell. A trickier case is a conjured elemental that stays put even after you lose concentration, until it's returned from whence it came at the end of the duration. In this case, I rule that the spell brought it here, but it's the creature doing the damage, not the spell, because it's a Thing that exists independent of the spell that brought it here (or can send it home by ending).

Given that the new Summon spells are "calling forth" a spirit which assembles itself in the space indicated, and only exists until it is destroyed, the duration ends, or the caster ceases concentration, I'd rule that it's a spell effect and not an independent Thing. Since Summon Undead is a Necromancy spell, I'd allow Grim Harvest to work, whereas I don't allow it with Animate Dead, since the undead that spell creates keep on doing their thing apart from the spell itself.

Just my reading of the rule situation, though. It's totally a DM call.

[MrCharlie]

Those same kinds of questions can arise with other spells, like Evard's Black Tentacles and Wall of Fire. Is it the necromancer doing the killing, or the tentacles? Is it the necromancer doing the killing, or the warlock who knocks somebody into the tentacles/fiery wall? I am inclined to rule those questions generously (treat Grim Harvest as applying to any damage coming from an active spell of the Necromancer's), and so I think I'd probably rule that way for things created from magic (Bigby's Hand, Mordenkainen's Sword, Spiritual Weapon, Summon Undead, Tiny Servant), although not to things summoned from elsewhere (Summon Greater Demon).

I could see it either way. Maybe I'd change my mind eventually and say "no if the things doing the damage is a creature with its own, separate actions and turns." I'd have to look at all the available spells and see what spells each ruling affects--there's no obvious place to draw the line.
There have been similar questions in scope raised on this forum recently regarding spells effect, AOE, and ending conditions via no longer being in them, and this is certainly a similar discussion. My personal take is that, if the spells says you deal X or Y damage, that's clear enough. If the spell says an object that you directly created deals X or Y damage, that's also good enough. If the spell uses your action to directly deal X or Y damage, that's good enough. But if the spell creates something that has independent actions, then we start to have issues. The fuzzy part (well, fuzzier) is when the spell lets you command or control the creatures you summon using a bonus action, but even then the creatures themselves are still taking the actions.

[Dragonhearthx]

There have been similar questions in scope raised on this forum recently regarding spells effect, AOE, and ending conditions via no longer being in them, and this is certainly a similar discussion. My personal take is that, if the spells says you deal X or Y damage, that's clear enough. If the spell says an object that you directly created deals X or Y damage, that's also good enough. If the spell uses your action to directly deal X or Y damage, that's good enough. But if the spell creates something that has independent actions, then we start to have issues. The fuzzy part (well, fuzzier) is when the spell lets you command or control the creatures you summon using a bonus action, but even then the creatures themselves are still taking the actions.

How about this. If the spell says anything to the effect of "use your spell casting modifier" it will activate Grim Harvest. Otherwise it does not work.
For example: conjure animals, You are using the animal stat block. While summon beast, you are using your spell modifier for its abilities.

[Witty Username]

I think I would rule in favor of it, partially disciple of life plus Goodberry logic, partially because it makes sense. Summon undead doesn't really summon a monster with any existence outside of the spell. If the spell summoned an existing creature or object them maybe but it doesn't. It is purely in the context of a spell effect.

[Kane0]

I would rule that it does