D12
From the White Wolf Wiki, the most complete White Wolf reference
A d12 — also called a twelve-sided die or, less commonly, a dodecahedron — is one of several standard polyhedral dice used in gaming. Each type is generally identified by the use of the letter "d" (for "die" or "dice") and the number of sides the die features. Multiple dice are connotated by an additional number prefixing the D. So rolling five twelve-sided dice would be noted by writing 5d12.
The d12 is one of the less-frequently used dice in the d20/OGL system.
