Peaks of Once-Great

Peaks of Once-Great enters the battlefield tapped.
{t}: Add X mana of a single color to your mana pool where X is the amount of basic lands in all graveyards of that color.
"Recklessness in the guise of protection. What did these Planswalkers do to this land and do they have a shred of remorse for their folly?" -En Verz