“The Colony was everything. They were born as one; they fought as one; and they died as one, driven by their hunger. But I hunted for something more.
I stole the sentience of an ancient power, and saw greater purpose. For we were the first--Auriga is our planet, and I will turn our hunger against those trespassers who would take it from us. One day, we will reign supreme on Auriga. And we will gaze up at the stars… still hungry.”

Every Major Faction in Endless Legend has their own unique Faction Quest. Completing (or at least putting effort into progressing through it) it is a good idea because:

1. it gives your Main Faction unique perks (technology, items, etc.)
   
2. you unlock extra rewards on the way (Dust, resources, and occasionally free Heroes)
   
3. completing the storyline is necessary for a Wonder victory (and the related achievements)
   
4. you learn the lore behind your Faction (and lore is awesome)

I’ve played around with every faction in Endless Legend (at least a bit), and I personally I found the Necrophages had the most interesting Faction Quest. Even if you don’t like playing as the Necrophages, their lore is nicely done and so if you enjoy Endless Legend, the Endless franchise (Necrophages appear in Dungeon of the Endless as well), or even just a good read, scroll on.

"Unease riddles the nest. I can feel it everywhere: In the hurried footfalls in the tunnels, in the huddling, in the lingering in the fungal gardens. They doubt me. The sifters, the burrowers, the soldiers, even the blasted groomers--get off!--they all doubt me, and their doubt seeps into my chitin. I sit in my lair, fret, fret, fret, fretting, while above hind-legs grow bolder, nipping and harrying and slicing at our tracks.
Enough! I must erase these doubts! But how? Doubts bite deeper than any jaws… Secure. Security. Yes. Above all I must ensure this region holds no threat for my brood. Otherwise they will come, fighters in leather and steel, with claws and weapons, to tear apart our fragile young. We will attack the hind-legs. Teach them that this place is ours, that we will not be driven out, be pushed away. They’ll stab and slice us, but the price will be worth it. My brood will survive. My brood will gain confidence. We will grow..."

NOTE: Only ONE version of this quest (either Digging In or Striking Out) will appear in one playthrough.

SUMMARY: He Who Meddles must destroy Minor Faction villages and armies that threaten the new Necrophage colony.
OUTCOME: "Triumph! Tonight the hive will reek of the dead, but we will spare some. One hind-legs, a traveler and fire-wielder, has learned our language, and stokes my curiosity with wild ideas..."

SUMMARY: He Who Meddles, leader of a breakaway Necrophage hive, must feed his people. To do so, he has chosen to attack minor faction villages.
OUTCOME: "Triumph! Tonight the hive will reek of the dead, but we will spare some. One hind-legs, a traveler and fire-wielder, has learned our language, and stokes my curiosity with wild ideas..."

"Sweet, sweet, sweet flesh. The nest thrums with fevered dreams, with faith, with belief. The workers scuttle with extra fervour, the groomers with purpose, the soldiers with mandibles high. The tunnels resound with the click and scratch of anticipation. Now’s the time to hatch, hatch, hatch more plans. To be a race who can command the surface as we command the dark, we must… evolve. The hind-legs calls himself Rhiss al-Khali and tells me he is a “scientist”--one who studies the ways of things. His quest for knowledge has led him far from his birth race, and he has roved the surface of this great land, learning much. I led him through the teeming hive, hoping to awe him, even frighten him, but his eyes sparkle with glee. He speaks of strange chymistries, and wishes to study how hind-legs and Necrophages differ. He teases me with ideas of a superior breed, marrying the best of both races. The other captives are more afraid of him than me. I don’t trust him, but he may be a great boon to us. To begin his experiments he needs special materials. I will ensure he gets them. And I will watch, carefully..."

SUMMARY: It is time to accelerate the evolution of the Necrophage. Find the resources needed for Rhiss al-Khali to start his experiments on the prisoners and the Necrophages.
OUTCOME: "Bloodcurdling screams issue from the captive pits, but this “Rhiss” learns much. Already the latest hatchlings show superior qualities. One day this land will be ours."

"All the captives died. All except Rhiss. Agony wrapped itself around him too, but unlike the others, he came out transformed. Patches of chitin cover his soft hind-leg skin, and only his eyes show the thing he once was. He has asked for a new name, and I have granted him his wish. He will be known as Ka-Riss. I never imagined a hind-leg could show such chitin, such single-mindedness. Maybe his experiments mark our path to victory. Menials! Fetch the hind-legs!
Every cycle I find myself seeking his company over the seething activity of my narrow-minded broodmates. His mind is as fertile as before, but now there is an edge of the untamed in his ramblings. What he truly wants remains cloaked in darkness, but I am beginning to think he does indeed seek nothing more than pure knowledge. He claims he can make us more numerous using materials held by the race known as the “Vaulters”--ancient enemies we’ve fought in the deep places for as long as the Giver of Remembrances remembers. He has been held in the hive long enough. Now I will test his loyalty, let him lead a swarm. Ah, he comes. Menials! Bring us some carrion!"

SUMMARY: Rhiss has been adopted; his name will be Ka-Riss. Driven by some ultimate goal, he speaks of valuable resources, needed for his experiments, that are held in a secret place by the Vaulters.
OUTCOME: "The enemy has been vanquished, their precious materials taken. Most pleasingly, Ka-Riss shows utter loyalty, and craves to begin working on the breeding chambers."

"Peace, peace, peace, can I get any peace? Every burr, every click, every scratch echoes through the hard tunnels, drills deep into my head. I need to think! To think is to see is to plan is to survive. But the noise! The noise distracts me from my tasks! Menials! Get out!
Ah, some peace. But a brittle one. Our acts have not gone unseen by the eyes of the hind-legs. They will be killed and feasted upon, but I fear for the day they organize themselves as well as we do. They will overwhelm us unless we have the numbers; our attention must turn to a new chamber. While we build it we will be vulnerable. The hive will need to be protected, the enemy scattered from our lands. Then? Then we can truly start swarming this world “Auriga”...
Rhiss has many ideas for how we might forages such a path. His mind is aflame, painting a blazing trail of the contraptions, strategies, and… unions… we might follow. While his mind burns, his body hardens and bends, becoming more like us every cycle. I never speak the thought, but he may be our future, a hybrid of hind-legs and hive-dweller that marries their capacity to reason with our brute strength. He has become more than a mere broodling, he has become an example. We must learn our enemies’ ways, watch them, find their weaknesses… But I get ahead of myself. Nothing will come without the brood mother’s new chamber."

SUMMARY: A new wave of Necrophages is to be hatched. Build the Fungal Laboratory to increase the fecundity of the hive, and protect the region while it is under construction.
OUTCOME: "The new chamber is built, the hive stronger than ever. Now our attention can turn to our enemy’s frailties..."

"What can you learn from a dead enemy? That was the question Ka-Riss asked me. A simple question, but a deep one. Answers skittered in the shadows, out of reach, until I finally understood his meaning. Nothing. Nothing can be learnt from a carcass, from a bag of bones wrapped in rotting flesh. Yes, we might feed, but we don’t learn. We learn the enemy by having one of them fighting by our side, or better, letting one of the enemy lead our own numbers. We wait and watch and learn. But how? I demanded. How do we convince a single hind-legs to join us, to reign death upon his own broodmates? You do not know men, he told me. They will betray their people, their land, even their own family for the right incentives. Money, power, pure simple hatred, he said, eyes gleaming as he looked up. He told me there are places--”marketplaces”--where the hardiest leaders from from different races can be bought, traded, sold. They will lead your armies and you will learn how men think, he said.
My carapace crawled with anticipation, but before he left he told me something profoundly troubling. It might all be for nothing, he said. His “science” tells him winters grow longer; some hind-legs claims it marks the end of days, even the death of Auriga. He scuttled away, leaving me with only the distant tic and hum of the hive. Maybe we must plan for this day, but now the light is dim and I cannot see how. For now we will learn the ways of the hind-legs, absorbing their bravest."

SUMMARY: Learn about the other factions on Auriga--to better destroy them--by hiring non-Necrophages Heroes and defeating enemy armies with those Heroes leading your armies.
OUTCOME: "Hind-legs lead our swarms, and we have learned much by watching them. But I fear the real enemy may not be hind-legs, but the land itself. We will survive, as always. We will endure!"

"Our plight consumes me. When I rest, instead of the soothing darkness that once cloaked me, I am flooded with visions of ruin. Rivers of fire cascading out of the depths. Hives crushed into nothingness. Mountains upturned, the land scrubbed of all life, hind-legs and hive-dweller all dead. When Ka-Riss is lucid, a state that escapes him for most of the cycles, he scratches incoherently about a machine--built by the ancients of this planet--that may be our salvation. He is my most accomplished leader in the field, but his mental regression, his slide into becoming yet another savage killer among thousands, fills me with dread. As my mind soars, his unravels. Maybe civilization will be beyond us. Maybe I am the freak, the monster, an evolutionary dead-end doomed to return to the dust from whence I came.
Whatever awaits us, whatever we will become, we must survive. I have decided I have no choice but to submit to his ramblings, let him lead a swarm to the bones of this “Endless” race. Therein lies an “Incubator”, a machine that will grant our unhatched immortality, let them live for countless cycles beyond the reach of flame and ice until the cataclysm passes. We will swarm over the lands, lay waste to our enemies, plant our eggs in every nook, every crevice that we can find, and in time beyond measure, when the stars have shifted, a new generation will crawl out onto a virgin land. Auriga, our birthright, will forever be ours."

SUMMARY: Rhiss has dreams of glory for the Necrophage--perhaps even greater than yours. Put him at the head of an army and send him out to conquer.
OUTCOME: "The machine is secured. Soon it will form the heart of the most important chamber we will ever construct. Soon we will raise a swarm the like of which has never been seen before."

"We are doomed. Doomed to be nothing more than unthinking killing machines. I have seen the evidence. The “Endless” made us to be killers, and they made us well. My hope that we might become something more than our nature lies in ruin; Ka-Riss’ degeneration into savagery is complete. Nothing occupies his mind other than the next fight, the next feed. We are killers. And I? I have found peace with that. We are what we are. And we will survive. The eggs that we will scatter to the darkest corners of these lands will see to that. Before that though, our numbers must fall until only the strongest, the most ferocious, the most tenacious stalk our hives. Only then will we ensure that the gene-line is ready for the challenges that await on the other side of the long winter. Starvation, banishment, sacrifice of the weak and feeble to feed the strong--the methods don’t matter, only the outcome. “Cruel”, the hind-legs might say, but cruel is better than dead.
Before we slaughter though, we must build. A factory chamber that can replicate this Endless “Incubator”, this strange machine that will keep our eggs out of time’s grasp, must be constructed. As I listen now, the hive is preternaturally quiet. My broodlings know change is coming. Soon though, soon it will ring with a thousand sounds of industry. And after? After it will ring with the shrieks of the dying..."

SUMMARY: Both Minor and Major factions must fall before the Necrophages. Assimilate Minor Factions, then cull the population so that only the strongest remain for the final onslaught.
OUTCOME: "The “Incubator” factory is built, and the weak have been culled. The time is near to scatter the seeds of our descendants across Auriga."

"The winters draw ever longer, and I foresee a time when the planet will be scoured of all life. Before that time comes we will swarm the surface, lay waste to all those whose paths we cross, and set the seeds of our descendants in the halls of ancient places. There they may find some respite from the coming storm. Whatever happens, we will raise armies without equal, and even if every last mortal dies, at least the stars will witness how the Necrophage swarmed Auriga, sweeping aside all who stood in their way.
We were made to kill, and so we will kill.
We are the Necrophage."

SUMMARY: The Necrophage hunger consumed Ka-Riss. Alone, you must prepare for the end of times. Gather Givers of Remembrance in one of your cities, reach Era IV in the Research Tree, then seed your eggs across Auriga.
OUTCOME: "If the winter devours us our descendants will rise--of that I am sure. And at times I dream that one day another will surpass me, and take us to the stars..."