Emergent Woodwurm is a rare Creature — Wurm card from March of the Machine Commander (MOC), collector number 37. Current market price: $2.69, TCGplayer market prices via Scryfall.
Backup 3 (When this creature enters, put three +1/+1 counters on target creature. If that's another creature, it gains the following ability until end of turn.) Whenever this creature attacks, look at the top X cards of your library, where X is its power. You may put a permanent card with mana value X or less from among them onto the battlefield. Put the rest on the bottom of your library in a random order.