[Spell weaving mastery][1]: 

> Damaging an enemy champion with an auto-attack increases your spell
> damage by 1%, stacking up to 3 times (max 3% damage increase)

**What is defined as "spell damage" for this mastery?** 

 - Does it refer to damage type (true physical magic) or any damage from
   abilities?
 - If it refers to ability damage, does the ability have to be castable?
 - What about item actives like hextech gunblade?

(I would appreciate if the answers are not based on guesses but rather on testing)


  [1]: http://leagueoflegends.wikia.com/wiki/Spell_Weaving_%28Season_Four_Mastery%29