Chief Chilly Challenge

Chief Chilly Challenge is an additional course in Super Mario 64 DS. The entrance to the course is in the Mirror Room of the Mushroom Castle, the same room as the entrance to Snowman's Land. However, the entrance is through the Wario painting behind the mirror, and only Luigi can get to it. When the player enters the room as Luigi, several Power Flowers are placed on the pedestals, and Luigi can use them to get behind the mirror and access the course. Defeating Chief Chilly at the end of the course rewards Luigi with the Wario Key needed to unlock Wario. Several Bullies are placed throughout the course. If Luigi falls out of the course or gets defeated, he will come out of the Luigi painting in the Mirror Room.

Layout
The player starts at the top of a large slide, and sliding down it flings Luigi into a gust of wind, allowing him to cross the gap and land on the platform across that has two Bullies. After the Bullies are four tilting platforms leading to a platform with a Bully, as well as a Wario Cap if he is unlocked. Next to this platform is a moving one with a Red Coin over it, leading to a large platform that splits in two directions. The left path has a strong wind blowing through it, preventing anyone other than Metal Wario from crossing. The path to the right is a cliff with a strong wind blowing upward, which tosses the player into a freezing pond below. Past the freezing pond is a platform with four Bullies followed by a series of moving platforms. The final area has a couple of Mr. Blizzards and a series of moving platforms leading upward to the entrance to the arena with Chief Chilly.

Boss battle
The battle with Chief Chilly takes place on a large octagonal platform. Like other Bullies, Chief Chilly attempts to push the player into the freezing water surrounding the stage. In order to defeat Chief Chilly, the player has to push him into the freezing water instead. Every time Chief Chilly is knocked into the water, he returns to the arena and causes it to shrink by jumping along the edges. Whenever Chief Chilly successfully pushes the player, he moves around the player. When Chief Chilly lands back on the stage a third time, the stage begins shaking, causing the player to slide around. The third time Chief Chilly is knocked to the edge, he remains there and tries to regain his footing. Pushing him into the water when he is trying to regain his balance defeats him and rewards the player with the Wario Key.

Missions
Two Power Stars can be collected in this course.

8 Red Coins
The first Power Star requires the player to collect all eight Red Coins. However, while it is impossible to backtrack past certain points throughout the level, all the Red Coins can be obtained on the first playthrough provided the player does not miss any. Ultimately, this is the only Power Star in a boss course that can be obtained on the first playthrough. These are the locations of the Red Coins:
 * Over the moving wire-frame platform
 * In the middle of the panel of normal coins in the air, over the freezing pond
 * Over the freezing pond
 * In the middle of all the Bullies after the pond
 * Two are over the moving platforms after the Bullies.
 * In the cage at the base of the platform with the entrance to Chief Chilly. By grabbing the Power Flower from the red block above, Luigi can turn invisible and enter the cage.
 * On a faraway platform. By grabbing Mario's cap next to the Star Marker and by using the Power Flower to turn into Balloon Mario, the player has to float over to the platform. On that platform is another red block containing a Power Flower, which the player must use to float back to the main part of the course.

After the player collects all eight Red Coins, the Power Star appears over the Star Marker near the entrance to Chief Chilly's arena.

Black Brick
This Power Star requires Wario to reach. Before the moving wire-frame platform is Wario's cap Luigi can use to turn into Wario, and after the moving wire-frame platform is a red block containing a Power Flower that Luigi can use to become Metal Wario and safely cross the path to the left without getting blown off. On the other side is a Black Brick, and breaking it reveals the Power Star.

Enemies

 * Bullies
 * Mr. Blizzards
 * Chief Chilly

Trivia

 * Chief Chilly Challenge is one of only three levels in Super Mario 64 DS that only one certain character can access, as only Luigi can pass through the mirror to this level. The other levels are Bowser in the Sky for Mario and The Secret Under the Moat for Wario.