[en] Different mechanisms of radiation damage of wide-gap metal oxides as well as a dual influence of impurity ions on the efficiency of radiation damage have been considered on the example of binary ionic MgO and complex ionic–covalent Lu_3Al_5O_1_2 single crystals. Particular emphasis has been placed on irradiation with ∼2 GeV heavy ions ("1"9"7Au, "2"0"9Bi, "2"3"8U, fluence of 10"1"2 ions/cm"2) providing extremely high density of electronic excitations within ion tracks. Besides knock-out mechanism for Frenkel pair formation, the additional mechanism through the collapse of mobile discrete breathers at certain lattice places (e.g., complex impurity centres) leads to the creation of complex defects that involve a large number of host atoms. The experimental manifestations of the radiation creation of intrinsic and impurity antisite defects (Lu|_A_l or Ce|_A_l – a heavy ion in a wrong cation site) have been detected in LuAG and LuAG:Ce"3"+ single crystals. Light doping of LuAG causes a small enhancement of radiation resistance, while pair impurity centres (for instance, Ce|_L_u–Ce|_A_l or Cr"3"+–Cr"3"+ in MgO) are formed with a rise of impurity concentration. These complex impurity centres as well as radiation-induced intrinsic antisite defects (Lu|_A_l strongly interacting with Lu in a regular site) tentatively serve as the places for breathers collapse, thus decreasing the material resistance against dense irradiation.