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.
Like the other Trio bird shrines and the Ilex shrine it can't be mined and is a One time use.
Along with the other Trio bird shrines it can be set to be reusable in the pixelmon.hocon by going into General and setting 'Allow bird shrine reuse' to 'True'
The command "/struc iceshrine" can also spawn a frozen shrine if the terrain allows for one.