From The Heroes of Might and Magic III wiki

Class	Water Magic
Basic cost	8
Duration	Instant
Level	2nd

Level	Effect
None	Target enemy troop receives (Spell Power * 20 +10) damage
Basic	Cost reduced by 2
Advanced	Target enemy troop receives (Spell Power * 20 +20) damage
Expert	Target enemy troop receives (Spell Power * 20 +50) damage

[edit] Heroes specializing in Ice Bolt

• Alagar the Druid

[edit] Units immune to its effects

• Water/Ice Elementals

[edit] Units extra vulnerable to its effects

• Fire/Energy Elementals