Enthrall needs attention
 

Enthrall (level 16 ench spell), when cast upon a mob already under the effects of Mesmerize (level 4 ench spell), will not overwrite Mesmerize, even though Enthrall is stronger than Mesmerize all-around. Mesmerize will overwrite Mesmerize, but Enthrall will not overwrite it.

Just tested - Mesmerize can actually overwrite the better mez, Enthrall. This could use fixing, please! :D