Potion of Direction Sense
When you drink this potion, you gain the ability to know exactly what direction and how quickly you are moving, including vertical movement, for 24 hours. In the case of teleportation, you know the direction and the distance teleported. The potion is separated into red, yellow, and silver strata such that the red part is in the northern-most end of the bottle at all times. As such, it can be used as a rough compass. Shaking the bottle fails to mix the colors.
A potion with the potential to foil a lot of dungeon confusion, like the Rotating Labyrinth, so why give it to the players? 1) So they can feel awesome when they use it to foil the Rotating Labyrinth. 2) As part of the intended solution to a puzzle, maybe a teleporting rooms puzzle where the rooms are not labeled. 3) In the hopes that they someday find an amazing use for it that surprises you.