While the role of asymmetric nitride clusters on the cage size and symmetry in fullerene-based structures is known, the role of the asymmetric arrangement of metals in nitride clusters on the nitrogen is not studied now. It is discovered that asymmetric mixed-metal nitride clusters give sufficiently narrow ¹⁴N NMR signals to make NMR the method of choice to characterize the endohedral cluster from the inside. In the series of mixed-metal nitride clusterfullerenes Lu_xSc_3-xN@C₈₀ and Lu_xY_3-xN@C₈₀ (x = 0-3) the δ(¹⁴N) values are found to be linear functions of x showing that ¹⁴N chemical shifts are additive values with specific increment for each kind of metal atoms. DFT calculations are performed to interpret the experimentally measured spectra. To reveal the main factors affecting ¹⁴N chemical shifts in nitride clusterfullerenes, shielding tensor components are analyzed in terms of Ramsey theory both in localized and canonical molecular orbitals. ¹⁴N chemical shifts in M₃N@C₈₀ and related systems are shown to be determined solely by nitrogen-localized orbitals, and in particular by the p_x,y,z atomic orbitals of nitrogen. As a result, the peculiarities of the nitrogen shielding in nitride clusterfullerenes can be interpreted by the simple analysis of the nitrogen-projected density of states and its variation in different chemical environments.