Author's Note: And now for an entry dedicated to everyone's favourite Suit Zombies! This is an example of a page that I intend to go back and fill in with more details as I progress the story.
Mr. President, In accordance with the recent mandate set forth in the wake of our uneasy alliance against the Unbidden and more recently the Prethoryn my Intelligence experts have been working to acquire all the information that we can concerning said uneasy allies. Let us begin with the most obvious threat then shall we?
Lich Empire: Biology
The Skeletons are what they themselves classify as Necroid in nature, for one of them to be born, another must first die, old age or disease is the preferred cause of death, battlefield injuries to a lesser degree so long as the body can be retrieved in time and the head is still intact. The process of 'Birthing' a Lich begins with a recently deceased body, they have shown a clear preference towards humanoids (Two arms, Two Legs, one head). Confirmed recipients of the 'ascension' include Flerken, (Most common) Draconians, Chozo and Humans. Also each one of them are psionic, just putting that out there. The corpse in question gets blasted with enough radiation to kill off all the remaining bacteria in their body and receives several cybernetic enhancements to increase mobility and augment functionality but near as we can tell from autopsies there is nothing to indicate cybernetics is the root of their consciousness. If you believe what they have to say about the matter then they seem to draw out the soul of one of their own that has been lost in 'the Shroud' for millions of years and stuffs it into the body that has gone through methodical modifications in a process called 'The ritual.' The suits that they wear everywhere, contrary to popular belief, has nothing to do with this ritual or the enhancement, the idea environment for a Lich is one where they don't have to deal with anything which would cause their bodies to decay and for that reason the suits are either vacuum sealed or filled with neutral gasses to prevent their bodies from decaying. The ritual process preserves a small portion of the bodies original consciousness word of mouth is that the better shape the subject's neural tissue is in the more of the consciousness pulls through so depending on how this works out you could possibly be looking at another eighty years of life tacked onto your life span. As a terrifying half metal skeletal corpse mind you, just keep that in mind.
Lich Empire: History and Culture
The first race to fall to this reanimation process called themselves the Zroni. They had the brilliant idea that the best way to keep the Reapers away was to detonate roughly 90% of all the Mass Relays in the galaxy which according to them also wiped out a ludicrous number of the tin plated pricks. The end result of this was simply put, reality breaking in several ways which is way we have things like worm holes and Hyper lanes. One of the other consequences of this though was the surviving Zroni praying so hard to live that they promptly unlived. The word Lich comes from a Zroni word meaning something along the line of boogey man. That's right, even they know they turned into abominations and they're still doing it. So realising that they had no other way to reproduce but to turn others into the same kind of abominations as them, and realising they were short on beings they could do that to they proceeded to dump a bunch of primitive extremophile bacteria on words that they figured could sustain life, erected a bunch of temples to themselves at places they figured would survive a few trillion years and filled them with doodads to alert them when beings evolved along far enough to come close to suiting their needs and wake them up so that they could start using them as fodder for more of the skull faced bastards. Which now leads us to...
Flerken Scion
Flerken are lion like humanoids standing on average at 6.5 feet tall. Originally a culture of primitive warriors similar ala the neanderthal's the first Flerkin to find the temple were subsequently abducted, experimented on and 'Uplifted' into a race suitable as fodder for the Lich's. The good news is that they for the most part left the Flerkin to their own devices after teaching them agriculture and medicine both in the interest of increasing their numbers, not that they did have to do much the Flerkin were already inclined to using violence to solve their problems and the introduction of the Lich's only served to galvanize them. Aside from handing out a divine edict to avoid head-shots and deploying 'Overseers' to collect the dead, which further led to the idea that the Liches were taking them to heaven. Constant fighting accelerated their technological development while evolving a culture that glorifies the idea of death in battle and by old age but decrying suicide and disease as a path to ascension. By the time they reached their world's first moon they were united as one race but that led to a new problem for the Lich's who had grown use to the extra bodies. As mentioned above the skeleton's aren't immortal, even with the majority of their race going into Cryosleep until needed but even that wouldn't last them for very long. There was the idea of trying to take other races as Scion's too but the first intelligent race that they ran into was the Lithloid trade union, whom they initially mistook as hostile synthetics. Course the Flerken were okay with fighting and dying on their gods behalf.
Flerken: Biology
Looking at the Flerken you can come to understand how they were engineered. They are a race of large humanoid lion like mammals engineered from the dominant predator on possess an enlarged Thyroid equivalent gland, not unlike that featured for the Dragoon Project, which in turn has resulted in dramatically augmented muscular structure and enlarged brain tissue resulting in high intelligence. However this enlarged Brain tissue has mostly been dedicated to their sensory organs resulting in enhanced hearing, sight, taste, smell and touch as well as enhanced reflexes and flight or fight responses/decision making. A good chunk of the population is Psionic, mostly because of their masters contact with the void it's suspected, and they receive training in the art of psionic warfare by their masters so watch out for that if we ever have to fight the cats. Other notable details is a meat heavy diet mostly for building up all that extra muscle they put on.
Lich Empire: Naval Combat
The Lich's ships comes in 7 different sizes, three of which are bigger than anything we have, and are outfitted with their own highly advance technology apparently stemming from having a head start from the ruins of another race coupled with having tens of millions of years to develop it. One thing that they have in common though is a minimalistic approach to their ships with long and narrow bodies typically filled with enough extra space for their highly advance technology and little else. Armaments tend to vary depending on what they're going out of their way to crack open but they favour the use of Zero Point Technology, psionic shielding, and Dragon Scale armour courtesy of their clashes with the Draconians.
Corvette Class: Casket
Small vehicle's like these typically contain the bodies of those the Lich's have brought back anyway despite being too damaged for the normal reanimation process. They've been hardwired into a extensive life support systems, which include a built in Cryo-cell that is typically active whenever the pilot is not in use with a computer supplementing the damaged brains which in turn is hooked into the ship itself, though the skeleton's have denied that these qualify as true AI's. They do however feature their own Psi-barriers stemming from their all psi population, primary armaments are laser based weapons powered by Zero Point Modules but they also carry several batteries of missiles to crack open harder targets. If they're damaged to the point that they may be destroyed they tend to crack open their Zero Point Module which typically warps space around the explosion sight breaking apart whatever the blast radius comes into contact with.
Destroyer Class: Grave Digger
If the Casket's job is to break open ships then it falls to the all too appropriately named Grave digger which flies in the wake of the Corvettes. Corvette pilots that survive the crucible of battle has their Casket Bodies upgraded to the Grave Diggers which as part of the second wave have a lower body count and better armaments. The unbidden proved a rich harvest with technology, the Matter Disentegrator to take apart the enemy forces once their shields and point defence has been cracked open usually exposing whatever hapless pilot was inside at the time to the vacuum of space, let that sink in for a moment.
Cruiser Class: Mortuary
This is where the big guns come in, for once the crew isn't hard wired into the ship and is crewed by both Flerken and Lich's after the first two waves finish off these guys come in and retrieve the dead for their blatant necromantic rituals. It's hard to get a read on what kinds of armaments these one have but they seem to come with a contingent of strike craft escorting them, possibly because they help to build them by, you know, snatching the dead off the battlefield. Usually by the time they've shown up the fighting is already over so we haven't seen them in action much.
Battleship Class: Graveyard
Unknown armaments. Believed to contain a sophisticated suite of bio-medical and cloning labs to compliment sizeable troop deployment.
Titan Class: Thanatos
Unknown Armaments.
Juggernaugt: Hades
Unknown Armaments.
Colossus: Anubis
This Colossus has been confirmed to possess the Divine enforcer as it's primary weapon, any planet on the receiving end sees all advance technology destroyed and the entire population gets converted to worshipping the bastard's. Banned under stellar treaty as a crime against sentient life.
Lich Empire: Ground Combat
Ground troops typically come in two variants, the Flerken Immortals and the Lich Necromancers which also makes for a dangerous and highly effective one two punch, we also see a return of grafting people into the pilot's chair for... reasons. Presumably good ones but it's best not to dwell on that.
Flerken Immortals
Similar to the Persians of Ancient Earth the Flerken immortals are named so for two reasons, the first is that they retrieve the body of everyone lost without exception, the second is that they can replace every troop loss on the field of battle no matter how many die, Unlike the Persians though this has significantly less to do with having a large population and more to do with having a complement of cloning technology onboard their ships which can manufacture new troops as fast as they lose them. Taking advantage of their strong bodies they prefer the use of heavy armour, which also helps to facilitate keeping their corpses intact enough to be ascended, which is usually paired with cloaks woven from the silk of a type of giant spider native to their home world. The silk has the tensile strength of steel but given the average strength of the galaxy's fire arms the cloak is largely ceremonial. If there is any practical advantages to the cloak it's that it obscures the body's frame making shooting them somewhere important that much harder. When they run out of ammo they tend to prefer melee typically in the form of a three sectioned staff with mace heads mounted on either side.
Lich Necromancers
Higher ranked psionic's among the Lich's, when these guys are deployed to the battlefield they raise both side's dead to fight for them. The Zombies retain their muscle memory from when they were still alive, if they still have their guns they can still fire them, if they were biotic as many among the citadel forces are they can still use them and if they were psionic then they tend to amplify the Lich's powers over the dead. There's also the matter to remember that before they could raise the dead every Necromancer was a powerful psionic which means possessing such abilities as attacking your mind directly with their telepathy manipulating the battlefield, and the people on it, with telekinesis. So yeah, look forward to every battlefield turning into a B-Movie zombie horror flick if we go up against these guys.
Vehicular Forces
Once again we return to the design philosophy of the Corvette, where we take horrifically wounded dying combat vets and strap them into car sized heavily armed vehicles. To begin with...
Scarab
A heavily armed tank like unit which walks along the battlefield on four crab like legs armed with lightning throwers for lethal, non corpse vaporising power to near instantly kill most things. They also like deploying their telekinetic field like a great big pillow to smother entire groups of enemies at once when the lightning fails them. That same field can be deployed so that it instead protects any of their other nearby forces.