Wand of cancellation

Putting one of these into your bag of holding will cause a magical explosion that will destroy your bag of holding and everything in it. Don't do this.

A wand of cancellation can be use to:
 * change potions into water
 * change scrolls into blank scrolls
 * neutralize monsters by taking away their special attacks

Among other special attacks MagicBane has a cancellation attack, which is similar to zapping something with a wand of cancellation.