Game version is v.2.00.5
Relent Gale almost works, but not entirely. It gives you a buff called Reject Gale when you use it that knocks back enemies within 1 range 2 times and knocks them down once, then the buff expires. The knockdown part does not work though. I've tried with Forced Move and casting Isendo twice (with Reject Gale active of course). I've also tried with the enemy right next to me, it pushes them away but no knockdown. I've also tried with them 2-3 spaces away from me, pushes them away but no knockdown. Works 100% of the time, can never get a knockdown.