Check Land

Dual lands that enter the battlefield untapped only if you control a land of one of two specified basic land types, otherwise entering tapped. Glacial Fortress wants a Plains or an Island, Dragonskull Summit wants a Swamp or a Mountain, and Hinterland Harbor wants a Forest or an Island. These reward an early untapped basic to come down ready. Distinct from Reveal Land, which checks a basic land type revealed from your hand rather than one already on the battlefield, and from Slow Land and Fast Land, which count how many other lands you control rather than checking land types.