I didn't make it!
you can hide characters in a map then trigger them to appear is there a way to do the opposite and make them re hidden.
Yes, in fact i am doing this in my next version of Unpredictable mod, the monsters and zombies will go to a retrite place and hide when cannot reach the player, then when they see a player is closer and reachable they will appear again with spawn FX effect !!! :-)