Damage types

In Dota 2, there are several different types of damage that can be cause by abilities and spells. Each type varies in how it affects enemy units. These types are magical, physical, mixed, pure, and direct HP removal.

Physical
Physical damage is caused by all regular attacks from all units. It is reduced by both Armor and Damage Block, is unaffected by Magic Resistance or Magic Immunity, and cannot effect Ethereal units. Examples of physical damage are Night Stalker's Void and Slardar's Slithereen Crush.

Magical
Magical damage is caused primarily by spells, although not all do magic damage. Magic damage is reduced by Magic Resistance, does not affect magic immune units, and does 1.4 times damage against Ethereal units. Examples of magic damage are Leshrac's Split Earth and Beastmaster's Primal Roar.

Mixed
Mixed damage is a combination of magical and physical damage types. It is reduced by Armor, Magic Resistance, and Damage Block, but goes through Magic Immunity. It does not affect Ethereal units. Examples of HP Removal are Beastmaster's Beastmaster and Leshrac's Diabolic Edict.

Pure
Pure damage is just that, pure. It ignores all damage reductions. It does not affect units under Magic Immunity and does normal damage against Ethereal units. Examples of pure damage are Chen's Test of Faith and Tinker's Laser.

HP Removal
HP Removal works by directly subtracting hitpoints from the affected unit. It ignores all damage reductions. It affects units under Magic Immunity and does normal damage against Ethereal units. Unlike all other damage types, HP Removal does not count as being attacked, so it will not interrupt Bottle or trigger any other on-attack effects. Examples of HP Removal are Necrolyte's Heartstopper Aura and Vengeful Spirit's Wave of Terror