Thiefbane

)   Thiefbane
Base item	long sword
Damage vs. small	1d8 +1 + level drain + cancellation + beheading
Damage vs. large	1d12 +1 + level drain + cancellation + beheading
To-hit bonus	+5
Bonus versus	@
Weapon skill	long sword
Size	one-handed
Affiliation	chaotic
When carried	(none)
When wielded	(none)
When invoked	(none)
Base price	1500 zm
Weight	40
Material	iron

Thiefbane is always generated in the inventory of One-Eyed Sam (unless wished for before Sam is generated). Thiefbane is typically generated with an enchantment, but the greater prize is the instadeath by decapitation (10% chance) on monsters symbolized by @.

Note that Thiefbane may blast you, even if you are chaotic.

Acquiring Thiefbane

Given that One-Eyed Sam is level 24 and carrying most of an ascension kit, it's probably a bad idea to simply engage him in melee. A scroll of earth or invisibility will fix One-Eyed Sam on his spot, and highly enchanted firearms or poisoned darts work fine for the kill. More suggestions can be found at the Black Market page.

However, this is not neccessary to acquire Thiefbane. If you are appropriately fast, armored, brave or stupid, and have the disarm technique and are wielding something you are at least skilled in, you can steal Thiefbane. Be aware that you still risk decapitation. If you try that, you will need an escape plan that works despite the Black Market's restrictions. One way is to apply (break) a wand of digging, trapping him (away from the door). Note that unless you are wearing an amulet of life saving, you don't really need an escape plan, since you won't be around to use it.

UnNetHack

In UnNetHack, Thiefbane's base item class has been changed to Two-handed sword and the player is in danger of being decapitated even if not in a form symbolized by @.