Here’s what I ideally would like to see to fix issues around Shadow Crash:
Remove Travel Time
Make it near instant and fall from the sky above the target. This reduces the chance to miss targets.
Bake Whispering Shadows into Base Ability
No one takes Shadow Crash without Whispering Shadows, it should be a part of the base spell.
Add New Ability: Shadow Feedback
The cd of Shadow Crash is reduced by 1 sec whenever an enemy afflicted with Vampiric Touch dies. This ensures that if a pack of low health targets die quickly, we’ll have Shadow Crash coming back up soon.
Change Mental Decay
Change it to work from Shadowy Apparitions, extending the duration of VT and SW:P by 1 sec when suffering Shadowy Apparition damage. This gives us back the AoE extension we had when Mental Decay worked with Mind Sear. It helps to alleviate the need to refresh DoTs towards the end of pulls when you need Shadow Crash up for the next pull.
I like the both of these ideas. Having to decide between refreshing dots or gutting your damage so you have SC for the next pull is annoying.
I doubt Blizz would give us both Shadow Feedback and change Mental Decay. They seem to want dot management to at least be a small part of our gameplay. Honestly either one would be good. Mental Decay working off of apparitions would give us basically permanent dots, so shadow crash would only be used once per pull.