To explore ambient strengthening and high temperature ductility, a combined forming approach of multidirectional forging and asymmetric rolling was proposed. A novel multicomponent ultralight Mg-3.11Li- 2.31Al-1.95Sn-0.94Y-0.45Er alloy was fabricated. The microstructural evolution and mechanical properties were investigated by microstructural characterization and tensile test. The combined forming results in remarkable grain refinement. The ultimate tensile strength and elongation of (255±7) MPa and 24.9%, respectively, were obtained at room temperature. The contribution of various strengthening mechanisms of the rolled alloy was obtained. Microstructural examination revealed the occurrence of dynamic recrystallization at 473-573 K and dynamic grain growth at 573-623 K. The maximum elongation of 293.9% was demonstrated at 623 K and 5×10^-4 s^-1. The dominate deformation mechanism at elevated temperatures is dislocation viscous glide.