Encounter Zekrom

When Encounter Zekrom enters the battlefield,
any one player may put a creature card named
Zekrom, Black Thunder from outside the
game onto the battlefield as an encountered
creature. It gains haste until end of turn.
At the beginning of combat this turn, each player
roles a d20. The player with the highest result
gains control of Zekrom, Black Thunder,
then exile Encounter Zekrom.