|A staff inhabited by a mighty demon, tricked and trapped in this form long ago. To survive, she now offers tremendous arcane power at a small price: a tiny portion of the caster's life essence, taken alongside the magic used every time its wielder casts a spell.|
The Majin-Bo is an extraordinarily powerful weapon in the hands of an experienced spellcaster, providing a universal boost to spellpower even before the +6 intelligence and MP are taken into account. Its vampiricism brand doesn't exactly make it devastating in melee, but its enchantment level is respectable, and it does allow you to recover health by crushing weaker foes by hand.
Unfortunately, it does have a few downsides. Unlike magical staves, the Majin-Bo is a two-handed weapon, preventing the use of shields. More importantly, you lose 1 HP for each MP you spend casting spells while wielding it (but it will not injure you further once you reach 1 HP). At best this effect is a mild annoyance, but at worst it can make any fight that gets out of hand significantly more dangerous. One cannot deny the appeal of this weapon, particularly for characters with massive HP pools or methods of recovering HP quickly.
Prior to 0.18, the Majin-Bo never spoke occasionally.
The Majin-Bo was added in 0.15.