At the beginning of combat on your turn, you may pay. If you do, gain control of target creature an opponent controls with power less than Yasova Dragonclaw's power until end of turn, untap that creature, and it gains haste until end of turn.
11/24/2014 The powers of the target creature and Yasova Dragonclaw are checked as you put the ability on the stack and again as the ability resolves. Once the ability resolves, it doesn’t matter what happens to either creature’s power.
11/24/2014 Gaining control of a creature doesn’t cause you to gain control of any Auras or Equipment attached to it.