Dead creatures can play sometimes

I am not sure what triggered that bug, but it occurred during the boss fight at realm depth 18. I was a tribalist with rank 1 in Forest Pack as the only learned perk; my team was Waspid Slicer, Brownie Mauler fused with Wicked Carver, Aaxer Apocalypse fused with Arcane Automaton, Cave Cockatrice, Waspid Worker fused with Unicorn Vivifier, and Waspid Guardian fused with Necrotic Clutches. I turbo played the fight, and at some point some of my dead creatures (but not all of them) started receiving orders and attacking as if they were alive. I do not know if they were supposed to be dead or if the bug is just that they APPEARED to be dead when they in fact were alive.