Dicekind

The Fluorite Octet are an enchanted set of dice (or a set of enchanted dice), possessed by [Vriska Serket].

Description
There are eight eight-sided dice in the set, and they appear to be composed of one of the blue varieties of fluorite. The numbering is different from either traditional Earth dice or human role-playing dice, as each side has a unique pattern of pips, including a triangle of pips for three, a parallelogram for four, a sort of arrow-shape for five, a hexagon for six, and a pattern for seven resembling the design of whatever that thing was on Vriska's left eye before she lost her [vision eightfold]. The design for eight is identical to that for seven, with a single additional pip set to the side.

Use
They are used by rolling the full set. Each one is considered unique - the result of the roll is determined not by the total number rolled, but by the combination of numbers rolled on each die. There are a total of 8 8, or 16,777,216 - possible permutations of rolled values. The attacks resulting from these rolls are said to be "highly unpredictable", and fortunate results are "devastating to even the most powerful opponents."