Activate Phyrexian Altar by sacrificing a nontoken creature, adding ({1} magic symbol) .
The creature dies, triggering Yedora, returning the creature from your graveyard to the battlefield face-down as a Forest land.
Activate the creature by tapping it, adding ({G} magic symbol) .
Activate Kamahl by paying ({1} magic symbol) ({G} magic symbol) , causing the creature to become a 1/1 Elemental that is still a land until end of turn.