Remove Grasp damage and buff its sustain

The mastery is too weak atm. extremely weak, generally due to the last nerf it received. the mastery does not do anything beyond the slight advantage it might provide in a 1v1 otherwise its pretty much the most useless keystone in the game. the new colossus feels better both in lane and out however champions that don't have ways to proc it and are tanky top laners are in trouble tbh.