From The Heroes of Might and Magic III wiki

Class	Fire Magic
Basic cost	16
Duration	Until target troops next action
Level	4th

Affected unit loses all Defense, but gains a lot of Attack

Level	Effect
None	Attack is increased by former Defense
Basic	Cost reduced by 4
Advanced	Attack is increased by former Defense*1.5
Expert	Attack is increased by former Defense *2

[edit] Units immune to its effects

• Efreeti/Efreet Sultans
• Firebirds/Phoenixes
• Giants/Titans
• Undeads
• Elementals
• Golems

[edit] Artifacts rendering your units immune to Frenzy

• Badge of Courage

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