The Z fighters had just defeated kid buu a few days ago and where recuperating on planet earth. Everything is normal with goku at king kais planet and vegeta training in capsule corp as everyone else was doing other usual activities although this would not last for very long. Piccolo was standing watch outside of gohans house a usual activity for him until he begins hearing faint screaming noises almost like tortured souls. Piccolo found this extremely odd as nothing like this sound can be heard on both earth or in hell. Piccolo then began to look for any signs of where this sound could be coming from. Suddenly it becomes much louder and the area around him goes dark with pentagrams spawning all around him. From these strange creatures began to spawn. These where brown humanoid creatures with spikes protruding from there body and blood read eyes. They started making low grumbling noises before darting around piccolo and throwing what seemed to be fire balls at him. Piccolo easily doged them as they moved fairly slow and got into a fighting stance.
He smirked and began taking the 8 entities on by himself. As piccolo landed a punch on one it just stuttered and began violently clawing at him although this alone was powerful piccolo wasn't harmed too much. He grabbed its arm "Is that the best you've got?"
He then threw it and finished him with a punch through the chest. This gave the other 7 a chance to gang up on piccolo wanting nothing more than his namekian blood. Piccolo then found himself struggling as ki attacks weren't good as they moved to fast and he couldn't just attack them as usually they kept their distance and took advantage of that very well. Slowly they did begging to die but they were doing a good round on piccolo. Once there where 2 left gohan rushed out and delt with the last to not powering up. "Piccolo we need to go to west city and see how everything is going."
Without a second thought they rushed over to the city to see how everything was going down there. As they got closer the encounters with these same beings got more and more frequent and becoming more difficult. Eventually once they got to west city it was a complete mess. They weren't just up against the imps. There were thousands more there. They quickly headed to capsule corp where they found vegeta. Vegeta was wrestling with a cacodeamon. He threw it into the air and unleashed a galick gun on it vaporizing the creature. Gohan ran up to vegeta and quickly asked "Do you know what these creatures are?"
Vegeta turned around and smiled smugly crossing his arms. "I thought you would have been finished by these little pests. If you must know bulma is working all of this out as we speak we just have to hold out." Once vegeta finished talking a dog like pink creature with robotic hind legs and no gur was almost able to get a hit on gohan but piccolo quickly dealt with it. "Whatever these are they need to be stopped and fast." "We need dad!" Gohan exclaimed
The pentagrams began forming again but this time 4 brown muscular creatures with dome heads showed up (Hell Knights). They quickly began giving them trouble fighting even vegeta. Vegeta powered up to super saiyan and gohan went into super saiyan 2. "You said you wanted a challeng!" Piccolo remarked as he was punched across the face and fell to the floor by one of them. They began to use a tatic where they would corner one and try and take it out with vegeta distracting them. This worked with them dealing with one. They quickly moved to the second one but half way through Tien showed up towering above them with a kikoho ready.