Eclipsed Realms

The colorless tap ability is the safety net, but the real design lives in the second line: a land that fixes into any color, on the condition that the mana only ever pays for one creature type. That constraint is what pays for the flexibility. A plain any-color land is a real cost to include; here the color is metered by tribe, so the card is only as good as your commitment to a single lineage from the octet it offers (Elemental, Elf, Faerie, Giant, Goblin, Kithkin, Merfolk, or Treefolk). The choice is locked as it enters, so there is no hedging your way into two tribes off one land; you declare, and the fixing serves that declaration or sits idle producing colorless. What makes the design sharp is that the restricted mana funds both halves of a tribal deck's costs: it casts the creatures and it activates their abilities, so a source of the chosen type can spend this land's mana on its own tap effects, not just come down off it. That closes the gap where tribal fixing lands help you deploy a board but leave you short when the payoff wants an activation. This is the tribal dual-land idea taken to its logical end: near-total color freedom, sold back to you one creature type at a time, with the colorless mode as the tax you pay for guessing your build wrong.