Symmetry engineering plays an important role, enabling us to tune the anomalous Hall conductivity (AHC) in various compounds. Depending upon suitable atomic arrangements or doping, one can alter the band structure in such a way that AHC attains a colossal value or, obtain a band structure that is topologically equivalent to that of a trivial semiconductor with zero AHC. We investigate the magnetic, electrical, and thermal transport properties of various topological magnetic Heusler compounds. We discover the first three-dimensional topological magnet Co2
MnGa, showing one of the highest AHC ~ (1600 Ω-1
) at 2 K and highest known room temperature anomalous Hall angle (up to 12%) and anomalous Nernst thermopower (~6.0 µV K−1
at 1 T magnetic field). Besides, we discover the first metallic intermetallic alloy compound Mn2
CoGa, with finite magnetization (2 mB
/f.u.), but zero AHC.