Guildpact Greenwalker is a rare Creature — Plant Rhino card from Alchemy: Murders at Karlov Manor (YMKM), collector number 17.
When Guildpact Greenwalker enters, you may choose a creature card in your hand. If you do, that card perpetually incorporates {1}{G} and gets +4/+4. Multicolored creatures you control have ward {2}.