Kayns' "bug" after new pre-season runes

Hi, After the new rune update, a sort-of standard build Kayn is able to have nearly 80% heals off abilities. If you build mercs, black cleaver, jungle item, spirit visage, titanic, and a deaths dance, for example, you can go from 450 health to 3.3k health with one Q to 2 champions. That's his whole health bar almost. If he went in on 5 champs at 1 hp he would be full health and then some. I understand it's ONLY an extra 15% on top of death dance 15% and his already 43% WITH spirit visages' extra little boost (5.84%) as well, but it still makes killing a Kayn nearly impossible if your team groups up ever so slightly (like 2 people near eachother in his Q range). Maybe I'm the only one seeing this as a problem, but after 4 years of playing, this is one of the most over powered champions I have seen now. He was never much of a problem before if you got a mortal reminder and didn't feed him, like every healing champ is, but after testing it with friends, even a mortal reminder and other burn items have little effect. Q-ult-Q-W and he will have maxed his health bar 3 1/2 times over. MAYBE just MAYBE this can be toned down. I have not played against one or played as one in a game, but from testing with 3 other friends as and adc, a tank, and a mage, all with burn items and CC , he really can't be killed and could easily 1v3 if not even 1v4 depending the matchup with all full build champs.