Mix

Exile each creature face-down, and shuffle those
cards. Separate those cards at random into a
number of piles equal to the number of players,
with each pile having an equal number of cards.
If piles can't have an equal number of cards, turn
an exiled card face-up at random until they can,
and separate the remaining face-down cards.
Then, starting with you, each player chooses a
pile, and returns each card from their chosen pile
from exile to the battlefield face-up under their control.