Activate Mycologist's second ability by sacrificing a nontoken Saproling or creature with changeling.
When the creature dies, Yedora triggers, returning the creature from your graveyard to the battlefield face down as a Forest land and as a 1/1 Saproling due to Life and Limb.
Resolve the Mycologist ability, causing you to gain 2 life.
Repeat.
This ingenious loop turns your graveyard into a revolving door of life and land by weaving together three seemingly disparate permanents. **Mycologist** provides the crucial sacrifice outlet to feed the engine, allowing you to regularly trade away your creatures to gain life. The magic happens because **Life and Limb** turns every Forest into a 1/1 green Saproling creature, meaning the face-down land returned by **Yedora, Grave Gardener** immediately enters as a creature land ready to be sacrificed back to **Mycologist** all over again.