Basically anything that is not caused by an Attack, with a few exceptions. Youre correct about Mabek's balance. Scutter's Vice or Skimander's Slipstrike on the other hand specifically says "Attack" so it is considered attack damage not ability. Pyris's Ignite is affected by ability dmg., same with things like Hulks' Pain Expanse and even main item effects like Enchanted Quill's little extra hit and Hydraquill Crest's retaliation dmg. Bleed and Poison are not due to them not "remembering" their source since they can stack together from multiple different sources, almost every other damaging debuff does count though. The other 2 main exceptions are redirected damage, such as from Voodoo Doll or Spearmen's Shield Wall, as well as Super Moves. These are treated as neither Attack or Ability to prevent doubling up on bonuses and as a way tp prevent infinite redirections (like if 2 people with Voodoos hit each other).