How far does a Lore Wizard/Tempest Cleric's lightning-damage Magic Missiles push the target back?

Question

Per the Tempest cleric's Thunderbolt Strike ability (PHB, page 62), lightning damage can push some targets back:

At 6th level, when you deal lightning damage to a Large or smaller creature, you can also push it up to 10 feet away from you.

So, let's say there is a 20th level character, which is 2 levels Lore Wizard (UA) and 18 levels Tempest Cleric. This character casts Magic Missile with a 9th-level spell slot (creating eleven darts). They use Spell Secrets to change the damage type to lightning. They then have all the darts target the same creature.

Would the creature be pushed back 110 feet, one for each dart?

Or would the creature be pushed back 10 feet, one for the spell as a whole?

Answer 1

110 feet

Jeremy Crawford confirmed that each magic missile dart is a separate instance of damage, at least in the context of concentration:

@JeremyECrawford Do you roll concentration for every instance of damage taken? id est every Magic Missile hit?

Concentration: "You make a separate saving throw for each source of damage" (PH, 203). Roll for each missile. #DnD

Barring anything that explicitly says that concentration is a special case that treats magic missile differently than other things (or that thunderbolt strike is such a special case), the only possible consistent interpretation is that each dart from magic missile is a separate source of damage. When you make it lightning damage, then you deal a separate instance of lightning damage for each one. Which means that, for each one, “when you deal lightning damage” is triggered.

The fact that magic missile darts deal their damage “simultaneously” is absolutely irrelevant: thunderbolt strike makes no reference to time in its wording. It only says “when you deal lightning damage.” So you roll the first dart’s lightning damage, and that point in the resolution of your turn is a point “when you [did] lightning damage,” so you push the target back 10 feet—and then you move on to resolve the next dart.

There is absolutely no basis in the rules or in developer commentary, that I have seen, that justifies treating them as a single instance of lightning damage for the purposes of thunderbolt strike, despite them being separate sources of damage for concentration. That is an inconsistent interpretation that would require special exceptions to the rules to justify, and no such special exceptions are written anywhere (to my knowledge).

Answer 2

10 feet

The key phrase here is when you deal lightning damage, since all the “hits” are simultaneous you only do lightning damage once.

Answer 3

It pushes the enemy back 10 feet.

Assuming level 9 magic missile cast from a Lore wizard with all missiles against one medium size target.

First we'll clarify whether it will push the enemy back at all.

when you deal lightning damage to a Large or smaller creature, you can also push it up to 10 feet away from you.

If there is a single instance of lightning damage you push the target back 10 feet.

...A dart deals 1d4 + 1 force damage to its target. The darts all strike simultaneously, and you can direct them to hit one creature or several.

The UA Lore Wizard's Spell Secrets allows the force damage to be substituted in the ability.

When you cast a spell with a spell slot and the spell deals acid, cold, fire, force, lightning, necrotic, radiant, or thunder damage, you can substitute that damage type with one other type from that list...

So we have 11 sources of lightning damage dealt simultaneously.

This answer by Jeremy Crawford confirms that each dart counts as a different source (in the context of triggering multiple concentration saving throws). From the player's handbook we see that concentration specifies making a saving throw for each source of damage.

Taking damage. Whenever you take damage while you are concentrating on a spell, you must make a Constitution saving throw to maintain your concentration. ... If you take damage from multiple sources, such as an arrow and a dragon’s breath, you make a separate saving throw for each source of damage.

However Thunderbolt Strike does not say "for each source of damage" It simply says "when you deal lightning damage".

So the bottom line is although there are 11 sources of damage there is only 1 instance of 11d4 + 11 lightning damage and hence the target is only pushed 10 feet.

Answer 4

If I’m strong enough to shove you up to 10’ away from me, and my buddy is exactly as strong as me and he is standing right next to me, and we both shove you at the same time, how far away from us do you land? According to Newton, you would land 20’ away, or at least your acceleration would be doubled, because the Net force would be doubled.

But here’s the real question. Why are we pushing things with lightning? How does changing the damage type from force to lightning create such a circumstance? Shouldn’t force damage be the more suitable choice of cause for such an effect?

Here is where we need to think about RAI. The designers write these rules as an abstract simulation of reality.

If each individual dart from magic missile is a separate instance/source of damage (and I think that’s been clearly established), I can see why JC would rule the way he did RE:concentration, despite them happening simultaneously. Your mind will be made aware, through your nervous system, of each source of pain/damage, and each will be a separate distraction that could potentially break concentration, hence a saving throw for each. “Ouch, my face!” and “ouch my knee!” are separate distractions, experienced simultaneously and the rules for concentration are simulating that reality. Maybe you can ignore one but not the other. Let the dice decide!

However, I don’t think the it follows logically to assume that separate sources of lightning damage would also carry separate forces (in the Newtonian sense) that add up to a net force on the target. After all, we are talking about lightning damage, NOT force damage. I think that what the designers are going for here is that cinematic effect where the electric shock knocks someone across the room.

So what causes THAT effect in reality? What is it that the rules are actually trying to simulate here? That question was asked here. And the conclusion that most people come to, there and other places on the web, is that it is in fact the target’s own muscles in spasm that provide the force that moves the target.

So it would not matter how many sources of lightning hit you at the same time, or even how much damage those sources caused. Your muscles would only be able to throw you so far when they went into spasm. Therefore, I think the RAI answer is 10 feet. I believe the designers used the wording “you can also push it” simply to reflect that Thunderbolt Strike is a battlefield control maneuver, not to evoke Newton’s second law.