The Great Hall, Hogwarts

Jason

A blast of debris sent Jason off his feet. When he regained his footing, Jason looked up. Out of the side of the Great Hall's wall, there was a gaping hole that reached from the starry ceiling to the floor.

Percy and the others rushed down, shocked to find that something was eating the Great Hall for dinner. Puffs of mist and smoke floated in. He could make out dim shapes in the misty fog and darkness. He heard gasps everywhere. "Dementors!" someone said.

"What?" another person replied.

"DEMENTORS! Run!" someone else screamed.

Jason could make out at least two hellhounds, and other Underworld monsters. Percy reached his side. "Dem-we-what?" he asked.

"Dementors, magical spectres that suck happiness out of a soul," Jason replied. "In extreme cases, they can eradicate a person's soul altogether."

"Oh... fun," Percy replied. Percy got out his sword. "Guess they don't see the hellhounds." Speaking of which, a hellhound leaped towards them. Percy spun around, his sword turning into a wave of death. The poor hellhound dissolved into a puddle of shadow.

The other hellhound also bounded towards them. Jason let loose a volt of lightning at a chandelier above the monstrous dog. The hellhound froze for a second, before the chandelier gave way and smashed against the dog. Another hellhound vanished.

From behind the hellhounds, a squad of four spartoi locked shields. He could hear Percy curse under his breath. Jason wanted to curse too. Spartoi were one of the most dangerous undead warrior, and fighting undead at night... was like eating a hamburger in the morning. Which is to say, not very practical.

These spartoi were armed to the teeth with bows, arrows, and shields. Some of the shield carriers also had pikes, while the archers stood behind them for protection. Piper, Annabeth, and the others reached them. "Charmed skeletons!" someone cried out. Instantly, the Great Hall was put to another wave of panic and confusion.

"Well, they are sort of right," Piper grumbled. The spartoit headed for them. In an instant, all their weapons were drawn.

"This is fun!" Thalia cried, hefting her spear high on her shoulder and grinning. Jason had an uneasy feeling that she wasn't kidding.

"Right," Jason replied. The spartoi were almost on them when Will's first arrow hit one of them in the eye. It exploded, causing blind light and heat to erupt out of the arrow, melting the spartoi.

The other three were onto them. Two of them carried shields, one of them also had a pike, and the other a sword. The lone archer behind them stepped back for better range. Nico didn't allow that. With one quick thrust, he vaulted above the other skeletons by jumping off their shields, then fell onto the spartoi archer, sword first. The spartoi bounced back, dazed and Nico used the time to cause the ground under him to give way, causing a sinkhole beneath the skeleton's feet. Needless to say, the spartoi was gone.

The other two rallied against Thalia and Piper. Piper screamed for them to drop their weapons, which they promptly did. Thalia on the other hand, rushed in, her Aegis making them back up as Nico slashed his hand across the air, causing them to drop to the floor, as a pile of bones.

That wasn't over yet. Groups of black, hooded demons with spectral wings that flashed into existence before disappearing had arrived. "What are... they?" Percy asked, gazing at the hovering demons.

"They're called oneiroi, daimons of nightmares, especially the violent ones," Jason answered. "The magical community calls them-"

"Dementors," Annabeth finished. Jason nodded.

"They are especially dangerous at night. Don't look at them in the eye," Jason warned.

"Why?" Percy asked.

Jason regarded him. "You do not want to know," he answered simply. The winged daimons were swirling closer.

"Expecto Patronum!" Jason heard shouts from behind. Groups of silver animals charged the daimons. Percy, Jason and the rest followed suit. The oneiroi scattered in horror. For an elated moment, it almost seemed as if they were winning. Suddenly, their patronuses froze. People gazed uncertainly at each other. Then slowly, out of the misty fog, a woman emerged from the rest.

"Perseus... Jack-son," she called. Piper looked at him worriedly. "Pers-eus... Jack-son," she called again. "Son... of Poseidon." Her eyes gleamed murderously. "We have... met again, for a... well attended... reunion," she smiled at him coldly.