How about the faction is based on the lore of time travel, they come from a universe where Einstein survived but worked for the Nazis, basically they are mecha Nazis who have perfected time travel and teleportation. they have captured units and technologies from Hundreds of thousands timelines, making their technology expensive but more effective. Maybe a cyborg superhero who has a short range or long range teleport and can summon troops one or two times to assist in battle from an alternate dimension
Their character design could be less Nazi-ish by saying their new leader has opted for more united and less-genocidal rampages in favor for better people relations so they had more units. And their super-power could be like a massive deconstructor that removes the structures, units,etc from its attack area, by literally removing them from existence.