A die with 9 rollable values, for those moments when the Bard does something wild and you want to give him "6d9" damage.
If the roll lands with a blank square up, you need to re-roll, otherwise take the value facing (mostly, since the triangle faces are not parallel to the opposite square face) up.
Supports are not necessary, but they may improve the quality of the numbers on the “bottom” faces.
The author hasn't provided the model origin yet.