As Cavern of Souls enters the battlefield, choose a creature type. : Add . : Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.
Cavern of Souls (PLCI-345s) - The Lost Caverns of Ixalan Promos (Borderless) Foil
As Cavern of Souls enters the battlefield, choose a creature type. : Add . : Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type, and that spell can't be countered.
: Add 
.