User blog comment:Tanooki1432/The Questions of the Age (Warning! May result in Nerd Rage!)/@comment-58609-20111013014051/@comment-78.80.54.128-20120525174820

If you meant the Hierarchy from Universe at War, then you're dead wrong.

They are an utterly assimilated race whose AI tech has advanced so far (along with their biotech) that it is completely indistinguishable from the organic parts of the race, which is beyond what the Novus (UaW also) or the Geth are capable of.

In their command structure, they are not unlike the Citadel, and they have achieved a twisted version of what the Citadel has always wanted: complete sovereignty over everything they see, though in the Hierarchy's case it almost always ends in the extinction of any non-Hierarchy races.

They are greater even then the Reapers. Even if they do not have sheer concentrated firepower on the scale of the Reapers (their ships would be more on the scale of ME vessels, though they would have a lot of Destiny Ascension-sized ships), their overall firepower and expansion would be enough to scare the Reapers.

Actually, the Reapers would have the most trouble out of anyone. The Hierarchy are the epitome of what they claim mortal races can never become. They are a union of machine and flesh so perfect that the two cannot be told apart, they feed and grow at a rate that even the Reapers cannot match, and despite being only ten thousand years old, the Hierarchy has carved out an intergalactic empire. Even worse is the fact that they achieved all of this on their own. They had no Mass Relays, no Reaper-built technology at all, and yet advanced faster than the Reapers themselves.

The Hierarchy is so large, in fact, that they are practically invincible as a race, much like the Tyranids. Their forces are too strong to be pushed back at any solid rate, and even if they could be pushed back, no race has the kind of technology to effectively strike at the Hierarchy empire's heart. It is simply too large.