[GSM]

I ran a test with the Galren badge Quaking Crystal Rose with my Ghost/BK Reaper build, and did the same with Board Shaker as it currently is.

Sublime Empress's turn.
Weak! Sand Shark takes 161 Earth physical damage. (Crystal Rose / Rebellion Trigger)
Sublime Empress's turn.
Weak! Sand Shark takes 128 Earth magical damage. (Board Shaker)

This was the exact same enemy.

When a base class skill can do more damage and have more utility than a promoted class skill, I start to have an issue. But I digress.

I agree with Snake's suggestion, although I'm a bit iffy on making it a 3 round cooldown. I'd say 2 round cooldown if anything.