Ookey, Interplanar Goofball

Companion -- If this card is in your opening
hand and you take a mulligan, remove it from
the game and it becomes your companion if
you have no companion.
When Ookey, Interplanar Goofball dies,
choose one at random:
- Put Ookey onto the battlefield.
- Return Ookey to its owner's hand.
- Shuffle Ookey into its owner's library.
- Exile Ookey.