Quick rundown of Reisen II's skills...
Innate gives bonus damage on the next strike every 8 seconds, though each hit she receives will lower that time required by 1 second.
D skill is like Yuugi's horn proc, but it's an active and it gives a massive aspd/ms debuff instead of stunning.
F skill is just... Lyrica's ult, except I think it only blocks physical damage.
R is IIW.
W is a massive aspd/ms boost for 4s (160% aspd boost iirc at max level, and she can attain 522ms with it on). The timer resets if she hits an enemy girl, like Chen's ult.
OP lunar rabbit. Dammit the big Inaba rabbit needs her range back to compete with this piddling whippersnapper.