Considered the greatest battle in history, Operation: Anchorage showcased the effectiveness of the winterized T-516 power armor.

Glacial Fortress

Glacial Fortress enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Bloomburrow Commander

Fallout

Glacial Fortress enters the battlefield tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

As this is entering, it checks for lands that are already on the battlefield. It won't see lands that are entering at the same time (due to Warp World, for example).

This checks for lands you control with the land type Plains or Island, not for lands named Plains or Island. The lands it checks for don't have to be basic lands. For example, if you control Watery Grave (a nonbasic land with the land types Island and Swamp), Glacial Fortress will enter untapped.