Oh wow AP itemization has so HP, yet this item exist for that purpose...
Well?
I don't see how's that a problem for AD champion?
The More Hp they have the more Efficient this Item is.
AP itemization give more HP but there is practically only 1 armor item available for mage.
Don't forget that if you Crit with BOTRK
You do 16% of their Max health, or if you have IE you'll Deal even more Damage.