Planar Nexus

Being every nonbasic land type at once is the whole trick, and it exists to feed the cards that count those types rather than the cards that make mana. The mana ability is deliberately bad: colorless for free, or a full generic tax to filter into a color, a rate no serious manabase would accept if fixing were the point. The point is the type line. This is a legal grab for any tutor scoped to a nonbasic subtype, it turns on every ability that keys off Locus or Gate or Urza's, and it lets one land stand in for a fistful of specific subtypes that would otherwise each demand their own slot. Cabal Coffers wants a Swamp, and this is not one: basic land types are pointedly excluded, which keeps the card honest about which effects it actually feeds. Any card that asks "do you control a Gate?" or "how many Locus lands do you have?" sees this as one of whatever it is looking for. The design descends from the Ravnica Gates and the old Urzatron lands, cards whose value lived in their subtype rather than their output, and consolidates that idea into a single land that answers every type-matters question simultaneously. The taxed color ability is the counterweight: a land satisfying this many searches and triggers cannot also be a painless five-color source, so it pays for its universality by being slow and generic when you tap it for anything.