Talk:Hextech Gunblade/@comment-86.110.170.230-20101112141252/@comment-96.48.24.227-20101122025810

They're not stacked together. It chooses whichever damage is higher; AP + flat damage, or 20% of target's HP. You'll start using the AP when you have higher than 125 AP, since most champions average out at 2000 base health at level 18, and you need -much- more AP if they have any health items at all. That is, unless you go full AP, you won't see any benefit from AP at all most of the times.