Squirrel Forest

Unless a Squirrel entered the battlefield this
turn, this land enters the battlefield tapped.
{t}: Add {g} mana to your mana pool
{t}, Sacrifice a Squirrel: Add one mana of any
color among permanents you control.
{1}{g}{t}: If a Squirrel entered the battlefield this
turn, create a Squirrel token. Then, if 4 or more Squirrels have come into play this turn, untap Squirrel Forest.