Energetic effects between halogen bonds and anion-pi or lone pair-pi interactions have been investigated by means of ab initio MP2 calculations. 1,4-diiodo-perfluorobenzene, a very effective building block for crystal engineering based on halogen bonding, is selected in this work both as electron-deficient pi aromatic ring and as halogen bond donor. Additive and diminutive effects are observed when halogen bonds and anion-pi/lone pair-pi interactions coexist in the same complex, which can be ascribed to the same direction of charge transfer for the two interactions. These effects have been analyzed in detail by the structural, energetic, and AIM properties of the complexes. Finally, experimental evidence of the combination of the interactions has been obtained from the Cambridge Structural Database.