Reins of Power

{2}{U}{U} · Instant

Untap all creatures you control and all creatures target opponent controls. You and that opponent each gain control of all creatures the other controls until end of turn. Those creatures gain haste until end of turn.

Motor: se resuelve a mano

Rulings (2)

You only untap creatures controlled by you and the targeted opponent, not all creatures.
Wizards of the Coast · 2007-05-01
It is perfectly legal for either or both players to have zero creatures. They give control of all their zero creatures as instructed.
Wizards of the Coast · 2004-10-04