During the second phase of the Lambach fight a large tentacle comes down to deal some physical damage and leave behind a large red bomb. This bomb is sometimes not visible to all party members.

This bomb still does damage to those who can't see it, although no particle effect spawn. Restarting your client doesn't fix the issue; rather it seems to randomize who is affected. Recreating the lobby has the same effect.

Love you, muah
The bois at Aisle Seven