Ruyi Jingu Bang (5e Equipment)
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Weapon (quarterstaff), legendary (requires attunement)
Ruyi Jingu Bang is the legendary staff of a great monk of ages past. It is said to be able to extend to the point where it can touch the moon. The Ruyi Jingu Bang (Ruyi Bang or Jingu Bang for short) is a magic staff that grows, and shrinks at will by its user. It seems to be weightless to the person it chooses, but nobody else can lift it as it weighs 17,550 lbs.
You gain a +2 bonus to attack rolls and damage rolls made with this magic weapon. When you speak a command word, the staff can expand at 10ft per round or to a specific length shorter than 15 ft. The maximum is undefined (DM Ruling).