King's Costume Ball

At the beginning of your upkeep, choose one that
hasn't been chosen —
• All creatures are legendary until your next turn.
• Choose a creature type. Each creature is the
chosen type until your next turn.
• Target creature becomes the copy of another target
creature until your next turn.
{bull} Each player chooses a creature they control, then
return all other creatures to their owners' hands.
Sacrifice King's Costume Ball.