I need help from any source.

okay, 50% reduced healing from all sources due to it being ARAM. playing , with , applying grevious wounds, going in when his ult is down. and i still lost almost every fight, and one particularly annoying one where he healed 200 per auto with the w adn thornmail passive, grevious wounds, and 50% reduced healing.

before anything i get it's not the luckiest comp, i get we had limited range, i'm not saying i should be able to 1v1 anything, but this champ litterally 1v4'd my team and had full hp by the end of it with grevious wounds activated. Isn't there anything i could have done to not get killed even when his ult is down!? What in the world am i supposed to do to protect my team when this champ can take all of us on as long as he has some form of minor support and not have to worry? Not snowballed in any way i don't get what i did so wrong to be have lost the game to a single champ.