The Mana Beacon

Lands you control can't be tapped for mana.
{t}: Add X multicolored mana in any combination where X is the number of lands
you control plus your devotion to green.
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Riku had been studying The Beacon's powers for days. Did it relate to the forge below? Did it hold knowledge The Library didn't? Finally, Melira walked up and began drawing mana from it.