Reincarnated With A Summoning System

What Cain wasn't ready for was just how normal he looked. It's an Incubus outfit like he's worn many times before, leather pants, and boots with many spikes and bits of chain mail. He's not wearing a shirt or jacket, and his burnished Bronze skin, with the usual zero percent body fat type heavily muscled physique of a Demon is showing. He flaps the wings he can feel, finding six jet-black and feathered appendages on his back. 

Between the wings and the 250cm height, Cain suspects he is a Fallen Seraphim or something similar. Checking his interface shows that his current form is called [Demon Progenitor Default], so maybe he is in the form of a Fallen Seraphim. In the myths of his home world the first Demon was a Fallen Angel. 

"Looking good this time. You should pick that form more often, use it to scare the children." Vala laughs, walking a circle around him. 

"You'd give them Nightmares for weeks. The Progenitors are a sort of evil that makes us all seem like model citizens." The Oath Breaker agrees, clearly eager to see that in person. 

"Alright then. We've got under a minute to go until the fight starts. Oath Breakers will scout the area until they find the defenders. The battle name doesn't give us any clues, but it sounds like a city, so they've likely got scouts out to warn them of incoming attacks. Eliminate all that you see and report back."

The Oath Breakers rush off the moment the command is given while the rest of the army waits patiently. It's only a few minutes before reports start coming in. Scouts in the open grassland beyond the forests. They're staying out in the open where they can't be ambushed and within sight of each other. 

Then more reports, it is indeed a city, open plan, no walls, no barriers. The defenders are Gnomes and Goblins. Level 235. That last bit could be an issue. Cain is level 160, Misha is a bit behind him, and damage against monsters scales, unlike damage between transfers.

They're 75 levels above him, so he can still do damage, but there will be a lot of reduction. 

"We'll need to be very careful with Mythryll this run. With the level advantage, they'll be doing a lot of damage. Unless you want to be a Lieutenant?"

Mythryll shakes her head. "Cloning them is a better use of the skill, I think. They're going to be all spread out between the Guild Houses with responsibilities and such. That's not for me."

"Your choice. We will keep you hidden in the shadows and the trees then, out of the line of sight, while we attack the city. If none of us go into the open, they'll think it's all one big army advancing through the woods."

The Oath Breakers have returned with a detailed outline of the defended areas. The city doesn't seem to be prepared for an invasion, or perhaps they're planning on guerilla warfare in the streets once the army breaks through their first lines of defense. They've got artillery scattered all through the city, making it much harder to eliminate than organized ranks and a standing army on what the demons refer to as Mole Dogs that is roughly five thousand strong. 

Cain isn't sure quite what to call for his Supporters, as they need to be human or Demon, and all his usual choices are neither. He doesn't know an excellent human Summoner he can use, does he? Going through the options gained from Gillibrand, he finds a human necromancer among the possibilities. That should work out well, as long as it lets him call his undead. Continuing the search, he finds a unique one—a Pestilence Demon with a class known as a Plague Mother. The description says her class can Summon Plague Demons, which Cain knows will be acceptable. 

His companion choices tripled after his level 160 upgrades and only the Spider Queen active; he calls an even dozen of them out onto the battlefield, along with four more copies of Misha for healing.

"Hello." The Plague mother drawls, her words gurgling in the throat like her lungs are full of fluid. She's tall at nearly 180cm but so slender he could close one of his Demonic hands around her waist. Her pale green skin and stringy black hair make her look like she drowned in a vat of poison, but her plain black robes are clean and dry. 

"Welcome. We need demons for this attack. Call what you can, and we'll get ready to charge." Cain smiles at the Demon, who repeatedly nods before her and her clones call on eight Lords of Decay and Twelve Blighted Paladins each. 

"There's so many of them. We shall rule the world!" Her laughter makes it sound like the Plague Mother is drowning before she stops and spits out a mouthful of nasty green phlegm. 

"Sorry about that. It builds up." Now her voice is closer to pleasantly human, with just a little gurgle to the tone. 

"This will be rough; they're pretty high level. So just do what you can, and I'll keep Summoning you back if you die." Cain explains, and the demons bow low in acceptance. 

"Anything for the Progenitors."

"The south side is weakest. There are a lot of forces there, but the roads are wide and branch off to give easy access to most of the city. The west looks much more undefended, but there is a canal inside the city that they've dropped all the bridges across, and the roads are narrow and winding, reducing line of sight."

"We've got some pretty big troops; it might be best to go with the wide streets unless one side has large yards and low houses we can simply trample over?"

"The East is the noble district. They've got walls around the communities, but they're low and weak. There are many guards on the patrol in the East, but they're private guards and not military, so guessing their skill level is impossible in a dungeon where everyone is the same level."

"Alright, here's the plan then. The palace is in the middle of the city, on an island. Taking it would take the city. But if we crush the commercial district in the south and the Nobles in the East first, resistance should be minimal at the palace. Form up, and let's get into position."

Cain places almost everyone in the south, with only two Plague Mothers and Four Oath Breakers attacking the city's Eastside as a diversion. One on one, their enemies will likely be more powerful than most of the summons, but the Lord of Decay is very durable, and the Oath Breaker is a master of ambush, with incredible damage output. 

There are signs that the scouts have noticed them before they begin to charge, mostly gnomes running for the city and shouting. Either something has limited their magical communication, or this Battle happened before the system existed, and they couldn't communicate directly with the other Guards.

Cain signals the charge when he sees the first guards running with warnings, sending forth a wave of demons while the three of them, plus a copy of Vala and the two Demonic spiders, wait in the trees. He's got his interface open to show him the state of his summons, so he can call them as they fall, giving the impression that more and more forces are coming from the same direction. 

The Lamia and Wrath Bringers were the first ones into the enemy lines, with the Oath Breakers teleporting behind them to attack the supply lines and artillery pieces before they could fire more than a few rounds. 

It's a slaughter, the Gnomes and Goblins might be high level, but they're lousy fighters compared to the demons. The area healing, buffed by the presence of the Lord of Decay, is enough to keep most of the demons alive, while the defense forces lack any form of spell casters during the first engagement. 

Once they start falling, reinforcements start flooding the main streets, then suddenly come to a screeching halt, with a full third peeling off to the East, where the diversion has begun slaughtering the Nobles. That's better than Cain had hoped for. Not only are the Nobles not sending anyone to help, but they've also pulled a good portion of the reinforcements away. 

Three of the Plague Mothers in the south have fallen, so Cain sends them all back at once, their Summoned forces getting the attention of the artillery in the city, which begin shelling the open fields as the Plague Demons charge. Right behind them, Cain sends a wave of Wrath Bringers and Lamia, most of whom were destroyed in the initial engagements. 

More screaming and shouting spread through the ranks as the Gnome's heavy forces, chicken-like magical constructs two meters tall, and the Mole Dog elites of the Goblins reach the battle. They've begun to rally the defenders, the mounted Goblins viciously attacking every Demon they see. 

The constructs don't fare as well, being larger and slower. Against a more human army, they might be incredible, but the Lord of Decay is a genuinely skilled baseball player. With heavy swings of a pilfered artillery piece, the giant demons are crushing the constructs in seconds. 

The battle had begun moving into the city streets a mere five minutes in to the fighting when a series of horns rang from the palace, and a three-meter tall Goblin General in polished silver armor charged down the main street to join the battle, along with a dozen golden armored Mole Dog Riders that the system identifies as Red Goblin Dragoons. 

Cain realizes they're about to face the first boss of this dungeon, and he's not sure the Summons can actually win the fight without help.