How do multiple Star Spawn Hulk interact with zone psychic damage?

Question

The Star Spawn Hulk has the following feature :

Psychic Mirror. If the hulk takes psychic damage, each creature within 10 feet of the hulk takes that damage instead; the hulk takes none of the damage.

The situation where multiple hulks stand next to each others and one of them takes psychic damage is dealt with here. For the sake of this question, I will assume the linked question's accepted answer's results, meaning that a single instance of damage can only apply once per target.

As such, the damage that was meant for a single hulk cannot be applied multiple times to another target, by "bouncing" back and forth between the two. But what about having a damaging effect hit multiple hulks at the same time?

Imagine the following scenario. You have a large number of hulks, huddled together around a single non-hulk creature. Now, have someone cast an AoE spell dealing psychic damage to all hulks.

There are two ways this could be resolved :

• The spell's damage is considered as a single instance of damage, and thus the non-hulk creature will only take the damage once.
• Each hulk takes its own instance of damage, and thus the non-hulk creature takes the spell's damage as many times as there are hulks in range to redirect the damage.

If valid, with the right setup, the second interpretation could lead to very high theoretical single-target damage (and delicious cheese in perspective).

Is either of those interpretations wrong? Or is it entirely up to the DM to decide how this situation resolves?

Answer 1

The non-hulk creature takes the psychic damage a number of times equal to the number of hulks.

Since each Star Spawn Hulk possesses the Psychic Mirror trait, a non-hulk creature suffers from the effect of the trait of each Hulk. The quoted answer explain why the damage is not reflected infinite times between the hulks, but a non-hulk creature suffer from the effects of the trait for each Star Spawn Hulk in range.

If there are 2 Hulks surrounding a creature in the depicted scenario, then the psychic damage should be multiplied by 2, if there are 5 then the multiplier is 5, and so on. The maximum number depends on the relative size of the creatures in the scenario: for example, a medium creature can be surrounded by 8 Star Spawn Hulks at most.

If the spell deals damage into an AoE to enemies and foes without distinction, then the number of times increases by 1, including the damage dealt also the the non-hulk creature.

Since this damage comes from different sources, this should be taken into account, for example in case the non-hulk creature is concentrating on a spell. Moreover, all this damage is taken at the same time: if order matters then the DM should decide how to proceed, maybe following the guidelines in Xanatar's Guide to Everything about Simultaneous Effects.

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Let's see it with a simple example.

Suppose that there are 3 creature, two Star Spawn Hulks and a Hobgoblin, each one 5 feet from the others.

A wizard casts Synaptic Static in order to include all the creatures in the AoE: all of them fail the saving throw and the spell deals 33 psychic damage. In this particular case the hobgoblin takes damage too, per spell description (emphasis mine):

Each creature in a 20-foot-radius sphere centered on that point must make an Intelligence saving throw. [...] A target takes 8d6 psychic damage on a failed save, or half as much damage on a successful one.

What happens is the following:

• The Hobgoblin suffers 33 psychic damage.
• The first Star Spawn Hulk uses its Psychic Mirror feature on the psychic damage coming from the spell, and reflects that to the other two creatures, since they both are in range. The hobgoblin suffers from the reflected 33 psychic damage, whilst the other Star Spawn Hulk is not damaged and does not reflects it due to the assumptions made in the question.
• The second Star Spawn Hulk uses its Psychic Mirror feature on the psychic damage coming from the spell, and reflects that to the other two creatures, since they both are in range. The hobgoblin suffers from the reflected 33 psychic damage, whilst the other Star Spawn Hulk is not damaged and does not reflects it due to the assumptions made in the question.

The hobgoblin suffer a grand total of 99 psychic damage: 33 from the spell and 66 (33\$\times\$2) from the Psychic Mirror feature of both Spawns. Beware that in this case the reflected damage cannot be halved with a successful saving throw, even if it originally came from a spell which allows it, and moreover the Hulk's trait does not contain such clause.