2y

I suggest an 8-sided die for the chaos die to represent the 8 directions of chaos as depicted in the universal chaos symbol (which should also be one of the faces). The symbol is a dot with 8 arrows pointing out representing all directions on a 2D surface. But there are actually 8 orthogonal directions in 3D space so the number translates in both dimensions. Eight is also a power-of-two, so has some connection to binary systems and is special because it is the cube of the only even prime number. Another symbol could be the Greek symbol of Chaos, which is a key that looks a little like the English letter 'K'. https://en.wikipedia.org/wiki/Symbol_of_Chaos