There are a couple problems I have noticed with these two abilities.

One, the resetting of the cooldown is bugged for lay waste. When you press Momentum Swing, it will occasionally reset it like it's supposed to, but then after about a second go right back to being on cooldown without being used! This may be WAI however; if so, please change the description. During the one second or so that it comes off cooldown, it is possible to still use the attack. However, this brings me to the second problem.

If you press Lay Waste or Momentum Swing too fast after another attack like cleave (and occasionally at other seemingly random times), it won't do the attack. As in, no roll happens but it does the animation and the cooldown starts anyway. When combined with the first problem, it means Lay Waste is hardly ever working.

I'm on Lamannia on a pure rogue acrobat using Mythic Bone Crusher.