The Rod of Varying Lengths

Peter the Thief's player has offered a lot of background for the character, including the possibility that he's royalty from a far-off kingdom. I was going to give him a ring that hints at this lineage, but ultimately I decided that would be quite the specific item to find in a side-quest. Then I started thinking about what sort of item might be useful to a thief. I really like this item, which may or may not have been inspired by the Ranger Pikes from Babylon 5 (Marcus lives!).

Rod of Varying Lengths
At first this item appears to be a thick rod of twisted wood about thirty centimetres long. When physically twisted, the rod will lengthen, becoming longer, but thinner the more it is twisted. The rod lengthens equally from both ends, meaning the person doing the twisting will remain in the middle of the lengthening object.

Baton Length

With a few twists, the rod can be lengthened into a baton or club. It can also be lengthened into a short staff (1.5m) or a long staff (2m). Beyond two meters, the rod is no longer rigid enough to be used as a weapon, but can be used as a thick cable for lengths up to 10m. Beyond 10 meters, the rod becomes flexible and rope-like and can be spooled out a full length of  20m.

The rod is a magical item and quite durable, having an AC of 12 and requiring 20hp of damage to sever, regardless of length.

As a baton or staff, the rod does d8 bludgeoning damage. Range 5'. Skilled welders (those with Simple Weapon proficiency) can quickly twist the rod, causing it to shoot out. This allows the welder to hit the rod at an enemy up to 10' away.

Once twisted to a desired length, the rod will remain at that size until twisted back, or if the welder rolls a Natural 1 while using it, at which time it will instantly snap back to rod size (automatically untying itself from any item or anchor). Twisting the item to a different length requires a Bonus Action.