The only items that cause % health dmg in the game are Liandries torement (sorry i misspelled it) and Bortk and for an AD caster like Riven, Renekton etc none of which is a completely cost effecent item...you guys think we shoul have a third option that shreds health based off physical damaging abilities or will it be to OP?  becuse i feel my options are limited late game agianst health stackers.

(forgive any bad english and reply constructively as this is only a theory and i am open to the fact i might be completely wrong)