Rennala, Caria's Last Queen

When this creature transforms into Rennala,
Caria's Last Queen or at the beginning of your
upkeep, each player mills three cards, you may
cast an instant or sorcery card from a graveyard without paying its mana cost. If that spell would
be put into a graveyard, exile it instead.
Whenever you cast a spell from the graveyard,
create an X/X blue Illusion creature token,
where X is that spells mana value.