The counter is skirmishers and/or raiders. Skirms (if fast enough) easily outpace mace and a strike comm, while dangerous, can't withstand a withering torrent from skirms.
Raiders counter due to weight of numbers both domis and maces in different ways. Domis are hard countered by numbers thanks to cooldown on capture and a ~400M build cost. Maces because for the 1 mace, you can get 3 scorchers, 5 bandits, 7 glaives, etc that can effectively dance around it and into your base, destroying initial metal/energy (energy early game might be more useful) production, causing a crippled economy early game.
My personal strat is the classic 5 scorcher rush to wipe comm or factory, preferably comm and as many mexes as I can get away with.
Edit: Another fun one might be the comm abduction.
