Shrines

A Shrine is a structure that spawns rarely in certain biomes. They are used to spawn the Legendary birds, Articuno, Zapdos, and Moltres. There are three types of shrines, one for each bird. Each of these shrines has a centerpiece that is modeled after its bird's wings, and when a fully-charged orb of the corresponding type is placed in one, the matching Legendary bird will spawn and battle the player who placed the orb. The orbs can be charged by defeating 375 Pokémon, which do not have to be the same type as the orb.

Activated shrines will emit redstone currents.

Biomes

Frozen Shrine (Articuno): Icy (Forge) biomes.
Static Shrine (Zapdos): Savanna (Forge) biomes.
Fiery Shrine (Moltres): Mesa (Forge) biomes.

Types

Fiery Shrine A
Fiery Shrine B
Frozen Shrine A
Frozen Shrine B
Static Shrine A
Static Shrine B

Config settings

The shrines can now be configured with encounter modes as listed with the shrine-encounter-mode in the config.yml file:

Once: A shrine may only be used once globally.
OncePerPlayer: A shrine may only be used once per player.
OncePerMCDay: A shrine may only be used once every Minecraft day (20 minutes).
OncePerDay: A shrine may only be used once every 24 hours.
Unlimited: A shrine may be used infinitely.

Trivia

Models up to version 8.4.3:

Fiery Shrine
Fiery Shrine
Frozen Shrine
Frozen Shrine
Static Shrine
Static Shrine