Being a tank doesn't mean to stack as much health as possible, high damage attacks and spells will lower your HP bar in a flash. So in others words get some armor and magic resist add to that the amount you get from activating Eclipse and we are talking of a really tough girl. Leona's main role is to get in the heat of battle, stun , slow and stop enemies and do it fast . Like i said I didn't focus on stacking health and so giving her a bit of AP for her abilities will make her a thorn in the *** for everyone.