Tranquil Guardians

Defender, Trample
As you cast Tranquil Guardians choose a color. Tranqil Guardians comes into play with X 1/1 counters on it.
{t}: Add one Mana of the chosen color to your Mana Pool for each 1/1 counter on Tranqil Guardians.
If X is 10 or greater, Tranquil Guardians loses Defender.