With a macro and a basic loop flipbooks are slightly scaled down and up creating a sense of movement while idling, I called it Idle Breathing.
Vanilla Doom just plays the first 2 frames of the walking animation but I prefer this.
When an enemy dies a corpse actor is spawned changing the collision shape and size and depending on the amount of damage received it plays a normal dying animation or one with explosion.
This corpse actor will be expanded so when damaged it explodes spawning flying gibs and blood squirts and pools.