Dungeon Warfare 2 2022 10 13 Dark Dungeon (1st Boss) 

if I remember right, it's an upgrade you earn

when you defeat the boss in this map

The slime trap slows and damages, it really helps

The game might have thought he was between the moving block and the wall, maybe the boss hitbox is bigger.

@@fabiojonlongzh I was able to reproduce it pretty regularly, there are a lot of slime traps in that corridor, plus the lightning traps damage and slow. I'm sure it's possible the crusher got him, but by the time he got there his health bar was already at like 20%, he wouldn't have lasted long even without the crusher.

they are upgraded so they generate money