6 NH4ClO4 (aq) + 8 Al (s) → 4 Al2O3 (s) + 3 N2 (g) + 3 Cl2 (g) + 12 H2O (l)
This is an oxidation-reduction (redox) reaction:
6 Cl-I - 6 e- → 6 Cl0 (oxidation)
8 Al0 - 24 e- → 8 AlIII (oxidation)
6 NV + 30 e- → 6 N0 (reduction)
NH4ClO4 is a reducing agent, Al is a reducing agent, NH4ClO4 is an oxidizing agent.