Sheesh, talk about a Grimdark BBEG you have there. You would want to be really careful about the personal history of your gaming group with that one.
I used to play Warhammer 40 roleplaying, maybe that's where the grimdark inspiration comes from. Actually, this devil isn't even the BBEG in the campaign, although it might be the most unsettling one. The campaign takes place in an island called Thule. This place was a prison-island for non-humans from Nebelmark, a place where I more or less based on "The Empire" from Warhammer fantasy. In Nebelmark they worship the Super-Human (name sounds lame in English, and in an English context Ubermensch sounds even lamer, but "Overmennesket" sounds cool in Norwegian, which is my native language). This is a former human hero-king that united the country and accomplished all manner of wonderful (and horrible) things, almost 800 years ago. Much like Sigmar in Warhammer fantasy. However, in later years, a militant wing of worshippers have ascended to power, one that advocates "cleansing" the world of non-humans, including elves, dwarves, etc.
Thule is in effect one huge concentration-camp, ruled by a viceroy appointed by the Nebelese emperor. The genocide of non-humans has been the focal point of the campaign. The player characters were dwarves, elves and priests of the old faiths, gods that were strong in Nebelmark before the hero-worship of the Uniter. They started the campaign by busting out of a gladiatoral arena, and have been gathering strength ever since. Now, at lvl 16, they have changed the island so much and stopped the genocide in Thule (but not in Nebelmark). Their goal is to make Thule a safe heaven for all the people persecuted in Nebelmark.
Thule was colonized by explorers from Nebelmark, but is still mostly unexplored. They know there used to be a great minotaur empire on Thule, the island is littered with ancient ruins from that dead civilization. And they have learned that the empire collapsed because of civil war following the introduction of Baphomet-worship. They have been unable to locate the ancient capital of that fallen empire.
The players never trusted Father Heinrich (The Lord of the Unborn in disguise), ever since they first visited his orphanage back when they were lvl three or four. The children were quiet, with blank faces, never smiling or answering anything other than yes or no. When they discovered he was a devil-worshipper, at level nine or ten, they didn't attack him right away because he was a valuable ally against the demonic influences of Baphomet, which at the time was the main enemy. (They destroyed the high priest of the Baphomet-cult at the end of heroic tier, but I have every intention to reintroduce Baphomet in Epic tier, when they finally locate the ancient capital: they will fight Baphomet there.) And also they might one day learn the truth about the church, the genocide and "Overmennesket". He is buried beneath the Spires of Humanity (the "St. Peters" of the church). A hint - he is not human.
The battle against the Lord of the Unborn was fairly epic. First they fought Father Heinrich. When he was defeated, which he was fairly easily, he transformed into his true form. He resembled a hydra, except each head was that of a zombie-like child. I used the stats for the hydra from Monster Vault, but also added that a person struck by the hydra's bite attack, also lost the ability to use encounter and daily powers (save ends). As a miniatyr, I used the
heroslayer hydra. The children at his orphanage also attacked the players, but they were no longer human children. The Lord of the Unborn had corrupted them, so that they resembled these creatures from the computer game Dead Space [ame="http://www.youtube.com/watch?v=0dvqAEwT-eA"]these creatures [/ame]
(I even showed a similar you tube-clip to them, and obviously asked them to disregard the sci-fi elements). They were minions. A total of 80 attacked in waves, climbing out from holes in the ground, hurling themselves from the ceiling, crawling from fissures, cracks and openings. The devil could eat one of these children (within range) as a minor action, gaining temporary buffs.
There was a large summoning circle in the room (the fight took place in catacombs beneath the orphanage, remnants from the ancient minotaur empire). When someone was knocked / pushed or slid into the circle, they were removed from the game 1 round and suffered 25 fire and necrotic damage. In effect they were transported to hell for six seconds. The heroes tried to push the devil into the circle, and suceeded once, giving them some respite.
As previously mentioned, in the end the heroes had to flee. The devil pursued them and crashed into the city streets, following the smell of children and rampaged his way to the hospital / midwife / daycare-center. The heroes rallied the city guard, the viceroy's armed forces and their own followers and henchmen, but were unable to stop the beast in time. It consumed 12 children (the maximum amount it could consume in a period of one day), and being full, it retreated back to hell.
The fight was very long and exciting, and the players REALLY wanted to kill this son of a ****. One of my players just recently became a father, and obviously his motivation to slay the devil was even stronger. His character vowed to finish Armariel, the Lord of the Unborn, in the future.
Fun was had by all.
