From The Heroes of Might and Magic III wiki

Class	Water Magic
Basic cost	8
Duration	1 round for each Spell Power
Level	2nd

Reduces the Attack of target enemy stack.

Level	Effect
None	Attack reduced by 3
Basic	Cost reduced by 2
Advanced	Attack reduced by 6
Expert	Affects all enemy units

Counters Bloodlust

[edit] Heroes that specializes in Weakness

• Cuthbert the Cleric
• Mirlanda the Witch
• Olema the Heretic