In an octahedral structure, the pair of d orbitals involved in d2sp3 hybridization is

In the formation of d2sp3 hybrid orbitals two (n - l)d orbitals of eg.. set [I.e., (n - l)dz2 and (n−1)dx2−y2 orbitals] one ns and three np npx⋅npy and npz orbitals combine together and form six  d2sp3 hybrid orbitals.