Frozen Shrine
A frozen shrine is a shrine that spawns rarely in Ice Plains, Ice Plains Spikes, Ice Mountains, and Cold Taiga biomes. In the middle of the structure is the shrine itself, which can be activated with a charged orb of frozen souls to spawn the Legendary Articuno.
The command "/struc iceshrine" can also spawn a frozen shrine if the terrain allows for one.
Blocks
Chiseled Stone Bricks
Frozen Shrine
Glowstone
Ice
Packed Ice
Stone Brick Stairs
Stone Slab