That night, everything was ready. Even if the information available to them was limited, the dragons were still confident that they could fully succeed in the rescue. Soon, their brother would be free again.
Haku had studied the plan perfectly. To prevent the guards from getting out of the tunnel entrance, he had decided that he would go inside the prison alone, while his sisters would keep the soldiers busy. Even if they were outnumbered, the cramped and narrow space of the tunnel would have prevented the soldiers from assaulting them en masse, allowing them to withstand even wave after wave. While they would form an impenetrable wall to prevent the soldiers from leaving and then call for reinforcements, Haku would enter using one of the mouse avatars and once far enough from the entrance he would extract a more powerful avatar from his dimensional bag with which he would way into the depths of that underground structure.
To increase the chances of success, all of them would use the most powerful avatars they had managed to create in their lifetime and with which they were most familiar. Haku was sure his sisters would make a good choice. In addition they would have on their side numerous runes of fortifications and various spells provided by Maldor. Even if all the guards inside the tunnel were level adamantium, they would be a big challenge for them.
Haku had considered whether it was the case to use his 'secret weapon', but he had rejected that hypothesis. Even though he had built it specifically to fight against a legendary level, and therefore possessed enough power to wipe out every human being in the entire underground structure, it was too large and too loud. And while he could have faced foes like Thornag and Hara, he couldn't have done so at the same time; Haku was confident that his weapon was capable of beating one legendary tier, not two. If he thought she could, then he would rather have used her to kidnap the king and use him as ransom long ago. In that situation, therefore, it was better to be more discreet.
So he had discounted the possibility of using the secret weapon. Even without it, however, Haku had avatars powerful enough to give him the edge in hand-to-hand combat. He would also use the invisibility rune to be able to sneak up on his enemies and kill them before they could react. Unless he met a legendary tier and Black Vulture, he doubted he'd meet any worthy opponents in his path.
The dragons waited until it was deep into the night, then immediately headed for the tunnel entrance. Almost as if fate wanted to help them, the sky was extremely cloudy, blocking the moon's rays and therefore hiding Haku and his sisters even more. In the previous nights they had watched the soldiers stationed at the tower, and therefore knew that they were not moving from their camp, therefore they would not have run the risk of encountering patrols. But even if someone was around, the dragons were already using an early version of the empowered invisibility rune, making them nearly impossible to spot. Once they reached what they now knew was the entrance to the tunnel, they immediately set to work. Maldor used a spell to move the air around them forming a viscous wall that blocked out sound. He couldn't keep it for long, since he would also have to fight soon, but his siblings only needed a few moments: using earth runes, they raised a huge wall that closed above them, sealing them completely from the outside world. Any sound that tried to escape, even the loudest, would first have to pass through a ten-centimetre-thick earthen wall.
"Now comes the hard part" Haku said, in the form of a little mouse leaning on the shoulder of Kotaru's avatar, who was a warrior composed of ogre muscles, great basilisk bones, and other powerful creatures. "As soon as the door is opened, all rush in and plug the entrance. And remember that the enemies will surely attack you in droves"
"We know it, brother" Kotaru replied as she drew a sword. Although the dragons felt more comfortable fighting exclusively with their bodies, and in fact had adapted their avatars to be able to perform this action perfectly, given the situation everyone had preferred to carry a weapon with them, in case their opponents proved to be too difficult. "You get ready to go in. And make sure you don't get crushed"
Haku nodded. The mouse he was controlling had extremely strong leg muscles, so it would be easy to move quickly. Even if he had tied his dimensional bag on his back and this affected his balance a little, he could still run with a moderate speed, at least for short distances. With such speed he was in no danger of being crushed, as he could easily dodge the feet of humans. "Okay, let's do it. On my three"
His sisters took up positions behind him, as if they were about to run for a long distance. Haku walked over to what they assumed was the entrance and then lifted the rat into a bipedal stance; on his belly was engraved a rune of nullification. "One two three!" and pressed it with all his strength.
After the usual flash of light, the ground in front of him began to buckle into a slightly angled door, which then swung inward as if the doors had lost the force holding them together. That wasn't an illusion, but a magic that changed matter itself. Haku thought that it was probably some kind of earth magic. As soon as the door was opened, Haku activated the rune of invisibility and rushed inside, followed by all his sisters who stopped a few meters from the entrance forming an impassable human wall.
As Haku had foreseen, immediately after the door was opened dozens of soldiers rushed towards the entrance with their weapons already drawn, and from the speed with which some of them were moving they must have been quite strong. Haku quickly dodged their feet, which would have surely reduced the rat avatar to a pulp if they hit him. No one noticed him: there was no way ordinary humans could see through the rune of invisibility, which, moreover, had been modified by Maldor and made even more powerful than before. Haku didn't meet any obstacles in his path and continued his downward run, quickly disappearing into the depths of the earth.
Meanwhile, his sisters were already ready for the charge that was coming against them. The first guards who showed up were carrying large halberds but, unable to swing them due to the narrow space, they pointed them at them as if they were spears. The dragonesses prepared to defend themselves: the halberds, despite their sharp point, could not have killed them (unless they aimed at the head), but the impact would still have been very violent, enough to make them lose a lot of ground. Considering their purpose was to keep the soldiers from getting out, they couldn't afford to back away even an inch. But even if they used their mana to fortify their bodies to the point of impenetrable, the force of the impact would still push them back. This left them with only one option, which none of them actually disliked; after all, it was common knowledge that the best defense was the offense!
As soon as the first wave of soldiers was close enough, the dragonesses who were in the front line, namely Corgorin, Serengal, Sisna and Malchia, rushed forward and lowered their bodies to their knees. Normally a human being would have ripped off all the skin and even force some of the flesh if he had moved at that speed in that position, but for them who could not feel pain and regenerated this was certainly not a problem. The soldiers were taken aback and did not have time to lower their halberds, and so the four dragonesses passed under them. As soon as they were inches away from the guards, they raised their weapons and speared them, then lifted their arm forcefully and split their bodies in two, severing them cleanly.
The action was so rapid that it was nearly impossible to see with the naked eye. One moment the guards were running, and the next the clink of weapons falling to the ground and a cascade of blood unleashed by human bodies splitting in two were the only hints of what had just happened. The blood that was released was such an amount that both the dragonesses and part of the walls were completely soaked even before what remained of the guards they had just killed hit the ground. The soldiers who were coming up behind them froze at the sight, but obviously the same could not be said of Corgorin, Serengal, Sisna and Malchia, who launched themselves against their opponents again.
This time killing them wasn't so easy: when the four dragonesses reached them, the soldiers reacted promptly and parried their attack, but since the impact was extremely violent and most of the energy had come from the attackers, the defenders were pushed back and in so doing they bumped into and hindered other guards. Such power, of course, was not only harmful from the outside: the muscles and bones of the arms of those who had parried the attack of the dragonesses were in fact brought close to the limit and if the soldiers had not used the mana to fortify their limbs, they would have broken off like appetizers. The force of the impact would normally have also debilitated the attackers, and therefore there would have been a moment of stalemate between the two sides, but thanks to the fact that they had ogre muscles and bones fortified with great basilisk plates, the dragonesses didn't have to worry about such effects and then continued to attack with even more ferocity than before.
Keita stepped forward, eager to join the fight, but Kotaru stopped her: "Let them have fun" she said.
Her sister glared at her. "I want to have fun too. If we all go to fight together we'll finish sooner"
"Our duty isn't to eliminate all these soldiers, but to prevent any of them from leaving" Kotaru reminded her. "We don't know if any of them possess a cloaking method or anything like that. If we scatter, someone might be able to slip out of sight and run away. But as long as we're all here, then even an invisible person couldn't get through. Also, if for if a stronger enemy presented itself, the latter would probably charge from a distance and therefore the force that would hit us would be extremely powerful; all united we can resist the impact, but if there are only a few of us in the trajectory no"
Tikka snorted. Kotaru was indeed the voice of reason in that case. "So we don't do anything?"
"We've already talked about it, we'll take turns periodically whenever those fighting have too damaged avatars" Kotaru answered. "Which could happen soon if those four keep fighting like that..."
Indeed, Corgorin, Serengal, Malchia, and Sisna were fighting completely oblivious to every blow they received, not even bothering to avoid taking too much damage. Only an expression of pure amusement was present on their faces: their eyes were narrow as two slits and a monstrous grin was painted across the entire lower half of their faces. They had always been the ones in the family who most enjoyed killing, but tonight they seemed literally possessed by some sort of madness. "Come forward, jailers of our brother! We could go on all night!"
If they had faced ordinary soldiers with that same ferocity, they would probably have torn an entire battalion in two in a matter of minutes, but in this case their opponents weren't weak. They weren't level adamantiums, but still they didn't have too low a power level, and they also had good equipment. The four dragonesses were able to kill several of them, but soon their avatars were too damaged to continue. But before the guards could finish them off, Kotaru, Tikka, Glausar, and Finiar leapt in front of them and took their places, as Kotaru had said, while their sisters dragged Malchia, Serengal, Sisna, and Corgorin after them. where they could regenerate peacefully. Using that method of trading, the group really could have kept fighting all night without anyone getting past their barrier.