Yara and Roku, Ivy and Moss

Forestwalk, flying.
Whenever Yara and Roku enters the battlefield,
create an Artifact token called Moss Diamond with {t}: add {g}. The token enters the battlefield tapped.
At the beginning of your upkeep, put a growth
counter on Yara and Roku. Then, if there are five
or more growth counters on Yara and Roku,
remove all growth counters and search your
library for a basic Forest card and put it on the battlefield tapped. Shuffle your library.