The Final Battle

When you cast this spell, exile all Legendary permanents and Adventurers on the battlefield.
During the next end step, randomly select one
of these exiled permanents to place into its
owner's graveyard. Repeat this process
until only one player owns cards left exiled this
way, then return those permanents to the
battlefield under their owner's control untapped
and with three +1/+1 counters if they are
creatures.