Alloying　is　an　effective　strategy　to　tailor　microstructure　and　mechanical　properties　of　metallic　materials　to　overcome　the　strength-ductility　trade-off　dilemma.　In　this　work,　we　combined　a　novel　alloy　design　principle,　i.e.　harvesting　pronounced　solid　solution　hardening　(SSH)　based　on　the　misfit　volumes　engineering,　and　simultaneously,　architecting　the　ductile　matrix　based　on　the　valence　electron　concentrations　(VEC)　criterion,　to　fulfill　an　excellent　strength-ductility　synergy　for　the　newly　emerging　high/medium-entropy　alloys　(HEAs/MEAs).　Based　on　this　strategy,　Al/Ta　co-doping　within　NiCoCr　MEA　leads　to　an　efficient　synthetic　approach,　that　is　minor　Al/Ta　co-doping　not　only　renders　significantly　enhanced　strength　with　notable　SSH　effect　and　ultrahigh　strain-hardening　capability,　but　also　sharply　refines　grains　and　induces　abnormal　twinning　behaviors　of　(NiCoCr)92Al6Ta2　MEA.　Compared　with　the　partially　twinned　NiCoCr　MEA,　the　yield　strength　(σy)　and　ultimate　tensile　strength　(σUTS)　of　fully　twinned　Al/Ta-containing　MEA　were　increased　by　∼102　%　to　∼600　MPa　and　∼35　%　to　∼1000　MPa,　respectively,　along　with　good　ductility　beyond　50　%.　Different　from　the　NiCoCr　MEA　with　deformation　twins　(DTs)/stacking　faults　(SFs)　dominated　plasticity,　the　extraordinary　strain-hardening　capability　of　the　solute-hardened　(NiCoCr)92Al6Ta2　MEA,　deactivated　deformation　twinning,　originates　from　the　high　density　of　dislocation　walls,　micro-bands　and　abundance　of　SFs.　The　abnormal　twinning　behaviors,　i.e.,　prevalence　of　annealing　twins　(ATs)　but　absence　of　DTs　in　(NiCoCr)92Al6Ta2　MEA,　are　explained　in　terms　of　the　relaxation　of　grain　boundaries　(for　ATs)　and　the　twinning　mechanism　transition　(for　DTs),　respectively.　©　2021