taultunleashed

I just found out myself
that when you do too much damange to mob and it starts glowing and show red skull if you press F button it your character will kick the mob, and it kinda explodes and you get double exp.

game dev probably put this intentionaly i just didnt know about it
till i pressed f button

This is a game feature, "F" is your melee action.
Whenever a mob dies and has a glowing red skull above their head, run up to them and press "F" and your character will do a finishing move.
This is a great thing to capitalize on, especially if you have have an XP bonus at the time.

PC

I guess ill move this to tricks and give like 100 points since im sure it will help some people.

This is a basic game feature. Any time the last attack on a mob is a critical hit they will get the skull above their head. Various animations for each type of damage that deals the last crit hit.