Some heroes such as Clinkz or Outworld Devourer can use auto-cast abilities that add damage to your hero's auto attack,
My question is: does this extra damage count as physical or magical damage?
For example, Clinkz's Searing Arrows add 20 bonus damage at level 1. If your hero's auto attack damage is 50, then are you doing 70 physical damage, or 50 physical damage and 20 magic damage?
Just want to know for the purposes of armour against people like this.
Best Answer
It does the damage type stated in the skill, regardless if it is an auto-cast ability or not. In your example, a Bone Fletcher with 50 base damage and Searing Arrows level 1 would do 70 physical damage per hit and an Obsidian Destroyer (Dota 1) with 100 base damage, 1000 mana left and level 4 Arcane Orb would do 100 physical damage and 90 pure damage.
Auto-casting does not change the damage type the ability inflicts. Also, there are some orb effects that have a little bit extra range when manually cast, such as Viper's.
If you want to find out which damage type a skill does, hover your mouse over the skill and hold Alt. There should be stated in green which damage type it inflicts.