Time from time you will encounter enchanted mobs, which are an ARPG staple. You will notice them immediately, as they'll be using magic tricks against you. These mobs could be anything from a simple skeleton to a massive spider.
So it's recommended to kill the enchanted mobs first, since they deal the most amount of damage than the rest of the ordinary mobs that use physical damage.
If you manage to kill such a mob, it may drop an enchantment it was using against you.