New summoner spell Idea

Hello All,

So recently I've been talking about this with my duo partner. I told him that I don't use exhaust anymore because it feels useless, especially when your getting 3/4/5 man ganked. What I propose is a new spell or replace exhaust spell, I haven't thought of a name, but lets just call it Hextech plating.

Hextech Plating - Cast upon a ally/self reducing damage (and possibly reflecting back damage) by X% amount for X seconds.

Think of it as a thornmail Ability. I feel a spell like this would be much more impactful then exhaust.

Thanks for reading, have a nice day/night!