Froglok Scryer (maybe enchanter mobs)
 

My brother and I went to kill the froglok scryer last night and the thing literally, just spammed the AE stun.

It is supposed to have a 12 second CD, however the thing was literally spamming it.

I know at the mobs level he could have 2 of the color spells, but it still wouldnt allow it to spam the spells like he did.

Same with cleric mobs, for instance, in the graveyard area in Mistmoore. On my alt I got stunned, literally from 100% health to death. Non-stop. Couldn't move.

Pretty much all NPCs have the ability to spam any of the spells in their level range with zero regard to cooldown times. It can get quite frustrating at times.