Banishing bell (Named Dragon's Bane in the NES version, orAmulet in the Game Boy Color Version) is an item in Dragon Quest II.
The Prince of Midenhall, The Prince of Cannock and The Princess of Moonbrooke can equip this to lower their resistance to the spells Fizzle & Snooze.
It can be purchased for 640 gold coins and sold for 480.
The Banishing bell can be found in a chest in the Sea Cave as well as being sold in the following locations:
It can also be won in the Lottery if 3 water symbols are matched.