Gain control of target creature until end of turn. Put a +1/+1 counter on it and untap it. That creature gains haste until end of turn. (It can attack andthis turn.)
11/17/2017 Mark of Mutiny can target any creature, even one that you already control or that is already untapped.
11/17/2017 The +1/+1 counter remains on the creature after the control-changing effect ends.