Pillar of the Paruns

A land that taps for any color, with a single qualifier that defines its entire identity: the mana only works on multicolored spells. That clause is the price for what would otherwise be a strictly-better five-color source. It produces nothing you can spend on a mono-colored card or an activated ability, so it lives and dies by how gold your deck is, though it happily casts a multicolored artifact or any other spell carrying two or more colors. In a build where every spell is gold, it reads as a perfect, untapped five-color source with no life cost and no basic-land-type requirement; in a deck with even a handful of single-color cards, it leaves mana stranded at the worst moments. The design captures something the color pie rarely lets a land do, which is generate any color at full speed, and pays for it by chaining the fixing directly to a deckbuilding commitment rather than to a tempo cost like entering tapped or paying life. It is fixing as a covenant: build wide enough across the color wheel and it rewards you with the cleanest mana available, but the reward scales precisely with how thoroughly you have abandoned monocolored cards. Few lands ask that much before they earn a slot, and few pay off as completely once the requirement is met.