Frost Legion

The Frost Legion is an event during which unique Snowman enemies spawn and swarm a player's Town (or spawn point if nothing has been built yet), similar to the Goblin Army.

Initial event
When a Frost Legion is summoned, a message will appear: The Frost Legion is approaching from the [east/west]!

The direction specified in this message only pertains to the initial wave of Snowmen, which spawns at the World's edge and travels to the player's original spawn point. Additional waves spawn immediately within the player's original spawn area. If the message says "West", the Snowmen will come from the left. If the message says "East", they'll arrive from the right. Note that these directions are not related to the apparent motion of the Sun and the Moon, which, in Terraria, appear to move from left ("west") to right ("east").

When the Frost Legion is about to begin spawning around the player's spawn point, the following message appears: The Frost Legion has arrived! and the theme music will switch to the "Boss 3" theme.

The Frost Legion event is much longer and harder than the Goblin Invasion and it is currently the hardest invasion in the game.

Completing the event
The event is completed when all the Snowmen in the legion are defeated. There will be 80 Snowmen, plus an additional 40 for each player that has a maximum health of 200 or more. In single player, the army will consist of 120 Snowman, while in an 8-player game, with each player having 200 HP or more, it will spawn 400 Snowman. With the maximum of 255 players above 200 health, the maximum number of snowmen in an invasion is 10,280.

When the final wave of Snowmen is on the screen, a message will appear saying, "The Frost Legion has been defeated!", and the theme music will return to normal.

Once defeated, Santa Claus will be available as an NPC and will move into an empty home, but will only be present between Dec. 15th-31st. Note that it is irrelevant whether the world is in hardmode or not to spawn the Frost Legion and thus acquire the Santa NPC, however in such a case you would need to bring in a Snow Globe from a hardmode world.

Snowman types
The legion will be made up of the following Snowman types:
 * Mister Stabby: A Snowman wielding a knife.
 * Snowman Gangsta: A Snowman that inflicts ranged damage with a gun.
 * Snow Balla: A Snowman that throws snowball projectiles.