If you're looking for a costume idea, here are some of the best! ... If you want to make your own, the original website has design specifications

White Witch costume and chariot from Narnia's The Lion, the Witch and the Wardrobe...

In the 2005 movie adaptation of C.S. Lewis' classic children's fantasy The Chronicles of Narnia: The Lion, the Witch and the Wardrobe, Tilda Swinton plays the evil White Witch, 'Jadis'.

Original movie costume and props
from The Lion, the Witch and the Wardrobe
Tilda Swinton's White Witch Narnia costume
Narnia White Witch warrior costume
Narnia White Witch chariot and costumeWhite Witch warrior costume Narnia movie
One of the costumes she wore in the film and the chariot she rode in the climactic battle scenes of the movie were part of The American Film Institute Showcase of infamous villain costumes at Disney's Hollywood Studios in Orlando, Florida on September 22, 2010.

The Chronicles of Narnia: The Lion, the Witch
and the Wardrobe movie poster
Narnia White Witch poster
Isis Mussenden was responsible for designing this amazing costume for the White Witch.

White Witch battle costume worn by Tilda Swinton
Narnia White Witch battle costumeWhite Witch Jadis Narnia costumeTilda Swinton White Witch battle costume
This outfit of chainmail and animal fur is her warrior battle garb and is much harder and less feminine than the other looks she sports earlier in the movie.

White Witch costume concept sketches
Narnia White Witch concept sketches

Actual White Witch movie costume
Tilda Swinton's White Witch movie outfitNarnia's White Witch battle costume
I think this wonderful costume would make a fierce Halloween outfit if you're looking for inspiration.

White Witch Jadis' battle chariot from
The Lion, the Witch and the Wardrobe
White Witch Jadis' Chariot Narnia movieNarnia's White Witch chariot and film costume
Narnia's White Witch battle chariot
Jadis rides this chariot into battle against the lion, 'Aslan's', army of freedom fighters at the climax of the movie.

The White Witch's wand prop from Prince Caspian
White Witch wand from Prince CaspianWhite Witch wand prop Prince Caspian
Also on display at Disney's Hollywood Studios within the Journey into Narnia: Prince Caspian theme park attraction was the wand prop used by the White Witch in the second movie, as she attempts to resurrect herself.

The Chronicles of Narnia: The Lion, the Witch
and the Wardrobe movie poster
Narnia's Lion, Witch and Wardrobe movie poster