Levitation is debuff. Mana shield cleaning it at cost of mana.
Levitation belt gives levitation, and... with mana shield it drains mana dry.

In one hand, exception will fix the problem.
In other hand...
Mana shield is already broken. It protects from both magic and physical damage. (If not mistaken)
Cleance is useful spell, but mana shield is automatic Cleance that cleaning debuffs without removing buffs. Maybe mana shield shouldn't clean debuffs at all..?
Or should it work only with water spell focus?

What do you think?