shadow crash is an instant aoe nuke that applies dots, sear is a channeled aoe that summons appiritions.
We need access to reliable dot spread at any given time a LOT more than we need more apparitions, a big number pump button though is fine as a CD.
It actually changes everything since it means you can easily apply dots at any point to a group and it takes shadow crash out of the single target rotation while bringing VT back into it, giving them both clear use cases instead of having them overlap.
alternatively you could make mind sear spread dots and shadow crash spawn appirations and it would probably be equivalent but i think having a chunky bolt that spreads dots is a better spender than a ticking channel that spawns ghosts. Dot spreading in aoe is a big sore point for shadows aoe, this would clean it up massively