From The Heroes of Might and Magic III wiki

Class	Fire Magic
Basic cost	16
Duration	Instant
Level	4th

All troops within a 3-hex radius take damage.

Level	Effect
None	Damage is (Spell Power * 10 +20)
Basic	Cost reduced by 4
Advanced	(Spell Power * 10 +40)
Expert	(Spell Power * 10 +80)

[edit] Units immune to its effects

• Efreeti/Efreet Sultans
• Fire/Energy Elementals
• Firebirds/Phoenixes

[edit] Units extra vulnerable to its effects

• Water/Ice Elementals

[edit] Heroes that specialize in Inferno

• Xyron the Heretic

[edit] See also

• Fireball