You have to unlock Luigi and then use his invisibility power to go through the mirror, if thats what you are asking.
don't no really
there is no mirror key. using luigi go to the mirror room, grab a power flower, and you can go thru the mirror no u cant it doesnt work
To get wario go to the mirror room as luigi.Get a flower to go through the mirror and get into the Wario painting. Defeat Cheif Chilly to get the Wario key.(I don't own the game,I am not sure defeating him will get Wario.)
Beat the Chief Chilly (Ice Bully). You need to be Luigi. Go into the mirror room and become invisible. Jump into the mirror and jump into Wario painting. You beat the Ice Bully and then you will unlock Wario's key. Happy Wario!
You need to defeat Bowser in the room that has the tap floor, then you will get a key that unlocks the downstairs door.
You need to unlock Luigi and have beaten Bowser in the Fire Sea. Go up the stairs where the second key should go, and into the giant mirror room. If you're playing as Luigi, ability flowers should be there. Grab one and run into the mirror, then jump into the Wario painting. Complete the course and you'll get the Wario key. Go to character room and go to the Wario door.
You have to go to the mirror room on the 2nd floor as Luigi. Get the flower on one of the stools and run through the mirror. Jump into the painting on the right and you'll battle Chief Chilly. Then you'll have the key to Wario's room.
Fight all of the enemies until eventually one drops a key. Bring the key to the door randomly positioned in the room, and use it.
The door to the Mirror room doesn't have a "You need a key symbol." It's just a door with a star on it. Defeat Bowser in "Bowser in the fire sea" and unlock the middle door on the second floor of the castle's main room. You will then enter a room with stairs that go in a circle. Go through that room and go through the door on the other side. Now you will be in a circular room of courses. Once past the "circular stairway" there will be two doors with a star on it in the room on two sides of the circle. Find the star door with the red carpet and enter. You have now found the room with the mirrors.
If you mean that door in the rec room in Super Mario 64 DS with the number 8 on it, you just need to get 8 stars and then it will open. The course with Goomboss, who holds the key to the room where Mario is locked, is behind this door.
When you have enough stars to open the room Mario's picture is in, go to that room & jump in the picture. In the level you'll see 2 tall tree stumps with a wooden bridge. Go to the shorter tree stump & climb to the top. Cross the bridge, & fall down the hole. Defeate Goomboss to get the key to Mario's room (the room with a "M" on the door). The room Mario's picture is in is behind the room with the mini-games & a picture of a beach.
Beet bowza