>>96301135
You fewl. Cataphractii are the least appropriate to be heavy weapon terminators. Oh sure heavy armor+slow speed=heavy weapon guy is the obvious association, but it is also wrong. Tartaros gives you the same heavy weapon capability while also being faster and more mobile which means it can more easily engage targets at closer ranges more easily without sacrificing all its protection while also being more capable in melee thanks to that mobility. Cataphractii might be better at taking hits but that's it, and that's not even mentioning straining the armor's carrying capacity.
Indomitus is actually the best siege terminator unit but people aren't ready to understand that.