Great Deku Chasm

(As a Siege enters, choose an opponent to protect it.
You and others can attack it. When it's defeated,
exile it, then cast it transformed.)
When Great Deku Chasm enters the battlefield,
search your library and or graveyard for a
non-Human creature card with mana value X or
less and put it onto the battlefield. If you search
your library this way, shuffle.
Plagued by the gloom, the Deku Tree needs to
be rescued from the darkness.