Armor is a stat shared by all units, including monsters, and buildings. Increasing armor reduces the physical damage the unit takes. Each hero begins with some armor which increases with level (Strike Freedom being the only exception). You can gain additional armor from abilities, items and talents. Armor stacks additively.
Damage reduction
Incoming physical damage is multiplied by a factor based on the unit's armor:
Armor > 0 : Damage multiplier = (100 / [100 + Armor])
Armor ≤ 0 : Damage multiplier = 1.0
Examples:
- 25 armor -> 0.8 incoming physical damage (20% reduction, +25% effective health).
- 100 armor -> 0.5 incoming physical damage (50% reduction, +100% effective health).
- -25 armor -> 1.0 incoming physical damage (0% reduction, +0% effective health).