Vivien's Arc Bow

At the beginning of your end step, search your
library for a green creature card with converted
mana cost X or less, put it into your hand, then
shuffle your library.
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"The Nura and Smaragdi combined their collective
magic into a unique artifact, the Arkbow, which
contained an invocation of every creature that ever
lived on Skalla. Their plan was to use the Ark bow
in a last stand battle against Nicol Bolas. But as the
forest erupted into flames and