Dual Land

The original Alpha/Beta dual lands: nonbasic lands that carry two basic land types, enter the battlefield untapped, and have no additional cost or condition to use. Tundra, Underground Sea, and Bayou are canonical examples, along with the rest of the ten-card cycle covering allied and enemy color pairs. They produce either of their two colors freely and count as both basic land types for any payoff that cares. Distinct from land_types.shock_land, which shares the two-basic-types template but charges 2 life to enter untapped, and from land_types.triome, which carries three basic land types and always enters tapped. Also separate from land_types.basic_land, since duals lack the Basic supertype.