From The Heroes of Might and Magic III wiki

Class	Air Magic
Basic cost	10
Duration	Instant
Level	2nd

Does lightning damage to target unit.

Level	Effect
None	Damage is (Spell Power *25 +10)
Basic	Cost reduced by 2
Advanced	Damage is (Spell Power *25 +20)
Expert	Damage is (Spell Power *25 +50)

[edit] Units immune to its effects

• Earth/Magma Elementals

[edit] Units extra vulnerable to its effects

• Air/Storm Elementals

[edit] Artifacts that render units immune to Lightning Bolt

• Pendant of Negativity

[edit] See also

• Chain Lightning
• Titan's Lightning Bolt