Arcane Comet is really bad design

In fact, every skillshot that aims itself is bad design outside of things like turrets because he has a reliable way to proc them. Stuff like this has too much counterplay without much interaction from the person actually using the ability. I mean, look at . Her tentacles aim themselves, so she really doesn't have much input in how to use them. On the other hand, she has tons of easy counterplay since the tentacles are both telegraphed and predictable. The same is true with comet, but it applies to every champion. Unless you have some form of reliable CC, this rune will almost never land on good players. Compare that with the versatility and reliability of old thunderlords and many mages who took that old keystone are feeling down or just taking Aery because it's much more reliable and consistent.