Zombieman vs. Pureblood

Yo, Vampire... get ready for a battle of attrition!" Zombieman vs. Pureblood was the battle between the S-Class hero Zombieman and the Demon-level mysterious being Pureblood of the Monster Association.

Prelude
Zombieman is going on a rampage through the Monster Association Headquarters, when he walks up a flight of stairs and comes across an army of monsters. Instead of attacking him, they goad Zombieman into fighting the powerful monster lying behind the doors. Zombieman goes through the door, and standing upside down from the ceiling is the vampire Pureblood.

Battle
Pureblood goes down to the floor, and at the same time, the monsters that were standing outside come flooding in to witness the battle between these two unfold. One of the monsters locks the doors to make sure neither opponent can escape. Zombieman asks why all of the other monsters are planning to gang up on Pureblood, and he responds by saying they're envious of his power. Pureblood states his intention to kill the other monsters when he's done, and asks Zombieman who he is. Zombieman begins an introduction, but quickly draws his two pistols and fires at Pureblood. However, the vampire manages to appear behind Zombieman and bite on his carotid artery. Surprisingly, Pureblood recoils, disgusted by the hero's terrible tasting blood. Zombieman gets back on his feet, while Pureblood, believing Zombieman to be using the last of his strength to stand, regales the hero with his history as the strongest and only natural monster in the Monster Association, being a part of a hereditary lineage of vampires. Zombieman reloads his pistols with more powerful bullets and fires at Pureblood, although the recoil from the ammo manages to break both of Zombieman's arms. Pureblood catches the bullets and throws them back at Zombieman, although he's surprised when he sees Zombieman still standing despite having his brain blown out. He realizes that Zombieman is the undying S-Class hero he had heard of, mocking his title of "phony monster", and also calling him the "phony human". Zombieman snarls at the monster, telling him to be silent, and proceeds to unsheathe two machetes. Pureblood mocks his sub-par fighting abilities while dodging his attacks. Pureblood forms a large wrist blade, which Zombieman manages to block. Zombieman slides his machete on the blade and attempts to strike Pureblood again, but Pureblood effortlessly dodges it and kicks the hero across his face, breaking his neck by turning it 180 degrees. However, Zombieman is still able to fire his pistol and creates a large hole through the monster's chest. A nearby monster laughs at Zombieman landing his first hit, so Pureblood rips the monster in half and drinks his blood. Pureblood sadistically laughs and tells Zombieman not to get ahead of himself, and proceeds to transform his body into multiple bats, which launch themselves at Zombieman and rip apart his body. The bats then go target two monsters in the crowd of monsters and suck their blood dry. Pureblood mocks Zombieman and asks him how he's doing; one of the bats is stuck in the hero's body, and becomes trapped as his body regenerates around it. Seeing how powerful the vampire is, he realizes that it is going to be a strenuous exercise and takes out his long-bearded axe. The hero asks the vampire if he's ready for a battle of attrition, and their fight resumes. Thirty minutes later, Zombieman stands victorious over Pureblood's bloody corpse with dead bats lying all around and heavy wounds on Zombieman. The dying vampire is shocked and confused at how the hero managed to still stay standing, even after he had "killed" him so many times. Zombieman tells the unresponsive Pureblood that he gave him about two hundred lethal wounds and it was a very tough battle indeed.

Aftermath
Zombieman walks to the door and prepares to leave, but falls to one knee at the entrance. The 30 other monsters remind Zombieman that he's not going anywhere, and prepare to gang up on him. However, instead of cowering in fear, Zombieman bends the steel bar, locking the door so none of the monsters can escape. The monsters are confident their sheer numbers can overwhelm him, and they proceed to do battle. After a long and hard-fought battle, the hero walks out of the room with absolutely grievous wounds, such as exposed ribs, a missing eye, missing lips, a large opening in his head, and his left arm hanging by a few strands of meat. In an instant, his left arm falls off. Zombieman believes it will take a few minutes to fully heal, and while his left arm is reforming, he takes a cigarette to relax. Then, Child Emperor calls Zombieman, along with the other S-Class heroes, to inform them that he has rescued Waganma and they're going to return to the surface. He also warns the heroes to be extremely cautious and not go too deep, for they will encounter extremely powerful monsters. Zombieman smiles, impressed by Child Emperor taking command like this, and with his wounds healed, prepares to go on another rampage.

Trivia

 * The battle lasted about 30 minutes.
 * In the webcomic, the battle was exclusively between Zombieman and Pureblood. All the other monsters are manga exclusive.