I got myself Mordenkainen's Tome of Foes, and am almost done reading through it. I made it to Star Spawn, and two things about the Star Spawn Hulk caught my attention:
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. In addition, the hulk's thoughts and location can't be discerned by magic.
Hulks are seldom encountered without a commanding seer nearby.
So I checked out the Star Spawn Seer, and it has two attacks that deal Psychic damage. One is a simple ranged attack, which is wonderful. The other one is melee, and imposes a condition, like so:
Comet Staff. […] plus 18 (4d8) psychic damage, and the target must succeed on a DC 19 Constitution saving throw or be incapacitated until the end of its next turn.
What I want to know is:
If a Star Spawn Seer hits a Star Spawn Hulk with a Comet Staff attack, and the psychic damage is redirected to creatures within 10 ft. of the Hulk, which creatures (if any) must make a Constitution save vs incapacitation?
I'm not worried about the Seer, as it is immune to psychic damage, probably for reasons like this. But I want to know, if I am running a Hulk or two against a party with a Seer nearby, whether I am going to have the Seer blast away with the ranged psychic attack or dish out conditions.