The current study investigated the self-focusing of a Gaussian laser beam under the cumulative impact of relativistic and ponderomotive nonlinearity. We reported quantum and magnetic field effects playing vital role in addition to relativistic and ponderomotive nonlinearity. The role of the magnetic field in amplifying the ponderomotive effect has been thoroughly investigated. The peak amplitude of relativistic-ponderomotive nonlinearity is found to be higher than that of relativistic nonlinearity alone. Furthermore, it has been reported that at high field strengths, ponderomotive effects are reduced. However, at broad values of magnetic field and beam intensity, ponderomotive self-focusing still appears to aid relative self-focusing.