Thunderlord's would have to be reworked into something completely different
for the other keystones masteries even compete. Right now playing Plat or Diamond is hearing the noisy chime thing sound it makes each time it goes off cooldown all the time, and sudden bursts of energy scoring first bloods and easy ganks here and there.
Things like Fiora, Xin, Quinn or Elise run rampant destroying everything within range. It's come to the point where 4 of 5 champions have the mastery.
Why not make it more utility oriented like it was supposed to, for mages?
Like, a bigger range, a small slow of 1 second and much lower damage.
It needs to be addressed, as it is right now It's just TOO good. Even if it had 1min cooldown it would be super strong anyway