Cultivated Lichen

At the beginning of each upkeep, you may tap another untapped, nontoken creature you control. If you do, create a 1/1 green Plant creature token.
At the beginning of combat on your turn, if you both own and control Cultivated Lichen and a creature named Ulvenwald Cultivator, exile them, then meld them into Assimilating Mass.
Carefully tended, it will grow and grow.