This took place in the Dilapidated Halls, adn I presume the other Secret Achievement takes place there. I assumed that the Drill was required but when I kept digging through wall per wall, my game crashed ;-;
wait do you mean the evil plushy becuse i had encounter it before and it was terrifying it's hp bar was different than other enemies also i had encountered it only one time so far (I'm currently on floor 11) and honestly when i first saw it i had panicked a bit and ate it (for the 100% completion of course)
ah ok but honestly i had been trying to 100% complete the game and i had unlocked an achievement called thousandanare (i can't spell and you need to have 10000 or more gold for it to unlock) and a cheat code for it witch if i start a new run i would start with 1000000 gold on that new run also i never seen that rage state before maybe it was because i ate and digested it before it entered it witch by the way was required for the 100% completion