Activate Kamahl's first ability by paying , causing the Forest to become a 1/1 creature until end of turn.
Activate Altar of Dementia by sacrificing the Forest.
When the Forest dies, Yedora triggers, returning the Forest land from your graveyard to the battlefield face down as a Forest land.
Resolve the Altar of Dementia ability, causing target player to mill cards equal to the Forest's power.
Repeat.
This elegant loop transforms your own land base into an endless mill engine by weaponizing the unique rules interaction between Yedora, Grave Gardener and Kamahl, Fist of Krosa. Since Yedora resurrects any dying nontoken creature face down as a Forest, the targeted land returns to the battlefield stripped of its previous identity but ready to be animated anew. By feeding this freshly returned land to Altar of Dementia, you trigger the sacrifice loop while milling your opponent out on the spot, relying on Kamahl's ability to repeatedly turn that land back into a creature for just one green mana.