Arcane Comet feels like a waste of a Keystone if you proc it on a non-immobilizing spell

Title. 2 Suggested solutions.

1. Make it only proc on movement-impairing effects (items with active slows, spells augmented by Rylais, spells with in-built slows or CC).

2. Reduce the travel speed by like 0.2 seconds but add a 1 second 20% slowing effect on the triggering spell hit so it's not blatantly useless keystone on non-slowing spell hits and it's not basically impossible to dodge on higher slowing poke spells (Camille W, Sion E, etc.).

I honestly find it baffling that Aery can even compete with Arcane Comet for the role of the better mage damage keystone whatsoever. It's so unreliable that the only champions (not even mage champions) with slowing poke spells as their only poke spells are the ones that are taking it while mages opt for Phase Rush, Aery and Electrocute.

The only two mages I can think of that run Comet predominantly are and , with being next but half the time still running Aery since his main poke spell doesn't slow.