Another tank support concept

So since there are not many popular tanks, most of populars one being Leona, Leona and Leona, there's a idea of a champion that should make something of a tank-enchanter.

So basically a champion that will want to build as tanky as possible, have some decent but not extremly op CC and most importantly, buff the adc and keep them alive. Honestly, maybe except some changes on Q values I think the kit is really balanced, and acutally I may need to add a lot of passive effects just to make it seems like a real champion in 2020.

Passive: After casting a spell, you and allies targeted by that spell take 10-80 (lv1-16) less damage (applied before piercing and defense) from all sources for 2 seconds.

Q: 20/19/18/17/15s CD Grant an ally or yourself a shield for 2 seconds of 20/50/70/90/115 + 20% of your maximum health (no bigger than 1000).

W: For the next 3 seconds deal aoe damage around you based on your max hp (and for sake of diversity and troll builds a small ap scaling, around 5-10% total ap), first time a enemy get damaged it's slowed by 60% for 1.5s

E: 25/22/20/18/17s CD A skillshot that stun the enemies hit for 1.5-2s and reduce their armor for 3 seconds.

R: 30/28/25s CD Passive: After casting a spell or hitting an enemy champion allies around you get bonus attack speed for 2 seconds. (not active when ult is on cd) (and to make it clear, the bonus will apply after you cast R, as it is not un cd until after you already tp) Active: After 0.25s teleport to an ally champion within 900 range, granting them bonus damage on-hit (20/35/50 + 0.1 ap) and 50/100/300 (10% of your bonus hp) extra max health for 2 seconds.