Spells: Tower of Frozen Shadows NPC spell cast

[Levlenna]

So, I was with my 56 mage in ToFS, 2nd floor. Low level mobs. Had my maxmum level earth pet up, pet lvl 45. fully buffed, with swords and Muzzle of Mardu and hasted.
One of the NPC's I am killing with my pet, starts to cast a spell: Beguile. Beguile is a charm spell that can charm mobs up to level 37. You already guessed it though, my max level pet gets charmed by this NPC, it roots me and kills me. Mages do not have a lot of health.
Had a similar experience on my lvl 52 necro. Not the pet gets charmed, but the level 52 necro gets charmed. How on earth is this possible with a spell casted by a low level mob, that can charm up to level 37?