Warrior %/s (KMS You & I + GMS Unleashed)

I believe everyone's claim for a buff is that Wingbeat is usable while transformed. Wingbeat overall will need to be re-evaluated since according to Baklava, Regain Strength won't activate if you don't move. Without Regain Strength, Wingbeat does significantly less damage, but is still beneficial to DPS.

I can confirm that if you stand immobile and not attacking/Jumping or using skills, Wingbeat wont trigger Regain Strength.
However, any action (Jumping, moving, using skills, attacking, whether you actaully hit anything or not) seems to make Wingbeat trigger Regain Strength. Its very clunky though, anything other than constant movement does not trigger Regain Strenght 100% of the time and sometimes there is a weird delay between Wingbeat hits and the proc.