There needs to be a %-maxhealth/second healable cap for PURCHASED-ONLY lifesteal.
Champions with lifesteal in their kits are balanced around it quite drastically.
Champions who don't have any but can just buy lifesteal have far stronger kits.
Also, glass cannon carries should never ever be draintanking.
On a side note, Warlord's is still disgusting. But that's a different matter.