The c2 invariant is an arithmetic graph invariant related to quantum field theory. It is defined in terms of a point count of the Kirchhoff polynomial of a graph and I will present a combinatorial technique for computing the c2 invariant by counting certain forests on a graph. As well, I will introduce a relation for the c2 invariant at prime powers. This result follows from a relation modulo p between certain coefficients of powers of products of particularly nice polynomials.