These dice are created in pairs, with a particular number in mind. Once creation of these dice is complete, these dice attach to the creator, and the number becomes fixed and unchangeable for the dice.
If, after being rolled by anyone except the one the dice are attached to, the dice show face-up, they will detonate. The detonation destroys the dice themselves, as well as anything else within 7' of where they land, tearing its way through anything softer than iron. The damage inflicted is both fiery and magical.
Possible uses: Left behind by a saboteur or assassin. As a source of distraction, as part of a larger plan.