When Overgrown Flats enters the battlefield, sacrifice it unless you pay .
: Add or to your mana pool.
Sacrifice Overgrown Flats: Add or to your mana pool.
, : Add one mana of any color to your mana pool.
.
: Add 
or to your mana pool. or to your mana pool.
, : Add one mana of any color to your mana pool.
