Originally Posted by ChaosLord29
. . . You know, I could be convinced that the Covenant could maybe take an Imperial Sector if they caught them unprepared or under-strength.
I really think that might be a stretch, unless they bring their entire force into it, this means High Charity and all their various armadas, and the stars must align in their favor. That means the Planetary Defense Force for all those worlds are totally useless (as they usually are,) Guard regiments are either off-system or underpowered, and there are no Spess Mahreen homeworlds in that sector. At best they MIGHT be able to take a subsector, but it wouldn't be long before, say, the Mordians or Catachans come in to curb-stomp some Elites.
Really the only vehicle of note that the Covenant have is the Scarab, but let's face it. It's only got one serious weapon, and against a moving target it's not that effective. Compare that to our favorite mac-mansion sized tank and it's 11 barrels of hell. Using a Warhound Titan against a scarab would be serious overkill, i'd say a Leman Russ or possibly even a Sentinel with a Lascannon and a bit of patience is all that's necessary to take those things down.