The problem with "Instant OFF GCD" abilities makes combat feel less rewarding.

[Kanzer]

I have died using Hallowed Ground many times and it was mission-critical...say...Phase 3 Titan. I'm just saying.

You know 'exactly' when mountain buster is going to happen. Being too slow to get hallowed ground up is not design flaw. You simply didn't think ahead and pop it when you needed to.