Yggdrasil, the World Tree

{t}: Add one mana of any color to your mana pool.
When you cast a creature with a color that is the same as at least one of the colors of mana used to cast it, put a +1/+1 counter on that creature when it enters the battlefield.
It balances the the realms of the universe. The gods created it so that everything could revolve around itself, thus preventing chaos.