Freyr, the Comming Spring

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When Freyr, the Ending Spring attacks, exile
the top 5 cards of your library, you may cast a
creature card revealed this way. Then, if that
creature's power was 4 or more, transform Freyr,
the Ending Spring.
If Freyr, the Ending Spring dies, exile it instead,
then return it to the battlefield at the beginning
of your next upkeep.