Amester the Harvester

Whenever you play a mountain pay {3}{r} to
create a 5/5 red dragon token with flying
Whenever you play a plains pay {3}{w} to gain
life equal to the number of lands you control
Whenever you play a swamp pay {3}{b} to create a
1/1 black crow token with flying for each land you control
Whenever you play a forest pay {3}{g} to gain {g} for each land you control