Ancient Monolithic

{t}, tap X untapped creatures of the same color,
blue or black, under your control: Adds X mana
of the same color as the tapped creatures.
—
Across the chasm, the wavelets washed the base of the
Cyclopean monolith; on whose surface I could now
trace both inscriptions and sculptures. Many characters obviously represented marine things which are unknown
to the modern world, but whose decomposing forms I
had observed on the ocean-risen plain.
Dagon—H. P. Lovecraft