I got 127% max health true damage as Fiora
http://i.imgur.com/CKTAeRo.png At around 600 AD you can kill anything with your ultimate no matter how many hit points they have.
This was my build.
EDIT: NOTE that this will pretty much not happen in a real game. In a real game it'll be closer to 40-50% max health true damage. My record was broken here
http://i.imgur.com/3yPpuxK.png?1
By Lord Dusteon.
If you want to get higher, just go into black market brawlers, buy a flesheater, and infinitely stack it.

