The Creepy Citadel indeed lived up to its name, as the haunted castle resided below the catacombs and crypt and may be the spookiest place in the Underworld. If he was correct, Chop Chop knew that also vegetarian zombies were here. "Well, here it is." A headless T-Bone said. "The Creepy Citadel, where the Eternal Undead Source rests in piece. Okay, if I remember, you four enter the castle through the main gate, then you fight your way through, reach the Ghostly Gateway, and find the Undead Source. Ok, I'll get the gate." T-Bone then used the key by inserting it in backwards (His head was on the other side), then turned it. The gate then lowered. "Now that's what I call using my head!" T-Bone laughed. "Good luck, and don't get scared!" And with that, the four Undead Skylanders ventured into the citadel. If Hex had read the history on this, a battle between a flying eyeball and a headless giant began here. When they approached the main gate, the suits of armor: Shadow Knights, suddenly came to life! "Sorry, but this dragon won't be slain so easily!" Cynder growled as she dodged a sword stab and shocked the suit when it tried to pull the sword out. Chop Chop dueled another, despite his size, and managed to overpower it. After the suits were destroyed, Hex used her magic to break the lock and open the gates, then the four of them ventured onward into the castle. And it was filled with traps, such as swinging saws on the ground, blades that could smoosh anyone between them, areas crawling with spiders, monsters such as zombies, Rhu-Babies, Rhu-Barbs, Undead Spell Punks, and Skeleton Archers ready to frighten them, ghosts that possessed objects (Which Ghost Roaster found tasty, since they were evil), and moving circle platforms. Once they were at the Gateway, Hex used her magic to teleport them to where the source was. They appeared at some sort of arena, which appeared to be the lower jaw of a giant monster statue. However, someone was waiting for them. And that someone was Kaos himself! "Well," The head said. "I bet you were just going to walk in here and take the Eternal Undead Source, EH? WELL, YOU THOUGHT WRONG! HA! Now, you're going to pay for meddling in my plans!" Then, he cast forth a Dark Imp Minion, who Ghost Roaster faced. He dodged a Skull Charge and countered with a Chain Whip. But the Imp seemed invincible in its Ectoplasm mode, but the spirit eater knew what would happen. The Imp was in Ectoplasm mode for too long, and it eventually exploded like a spirit bomb. This only annoyed Kaos. "BAH!" Kaos said. "He means nothing! You still won't be leaving the Land of the Undead! Ever! AGAIN!" He then began to harness the Undead Source's power to bring forth a nightmarish barrage of white and red lasers! During this, an evil Dark Dragon Minion was summoned, which Cynder fought. It reminded her too much of her own evil past. The minion became a shadow to avoid a lightning breath attack, then the two took to the skies. Eventually, the minion was down and the Skylanders survived the spell. "HUH? No matter, plenty more where that came from!" Kaos said. He then summoned another minion, this time taking the form of Chop Chop, which the Arkeyan faced. The two swung and blocked with their swords and shields, with Chop Chop trapping the minion with Bone Bramble before one more sword swing to finish him off. Next, a Witch Minion faced Hex. Hex blocked Phantasm Orbs with a Wall of Bones, then conjured a Rain of Skulls behind it. After many spells were cast, the Witch Minion had melted in defeat. Then, Kaos unleashed everything he had, with all four minions AND the Undead Source's power! However, the real deals were able to prevail! "WHAAAAATTTTTT?!" Kaos wailed. "But how can this be?! IMPOSSIBLE! Ok, you may have won this time, but the remaining two Elemental Sources, you will never obtain! EVER!" Kaos then fled, and the Eternal Undead source was for the taking.
"Skylands is growing darker." Eon warned. "But now, you have brought the Eternal Undead Source. Add its power to the Core of Light." Hex then used her power to insert the source inside. Then, she sensed ghostly spirits from inside the machine. Then, they flew out of the core! Gill yelped and due to the shock, Eruptor barfed out a little lava. Ghost Roaster knew they were good, and he wasn't hungry. Then, the streams of water gushing out became an eerie mist. Now, all that was left now was the Eternal Fire and Magic Sources. The Fire Skylanders then prepared to get the Eternal Fire Source. The leader of the four, Eruptor, was a volcanic being who could erupt when mad. Ignitor was a fiery spirit encased in a cursed suit of armor, after a witch had tricked him into thinking the armor could withstand a dragon's fire. Flameslinger was an expert archer, which had a blindfold to prove how good he was. He also had a bow that shot fire arrows and a pair of magical boots that left behind a trial of fire wherever he ran. Sunburn was part phoenix and part dragon with the rare ability to teleport. He joined the Skylanders to protect himself from greedy hunters and wizards. They had just discovered a new area in the Ruins, which had a train. If Hugo's research was correct, the Ruins, or Eon's Citadel was also called Ancient's Peak, which was referred to as the lost citadel of the Portal Masters. Diggs, who appeared to be there, explained that the moles were digging for an ancient artifact called The Crucible of the Ages, which was necessary to rebuild the Great Machine, and the only relic that could contain the Fire Source's power. However, a cave-in occurred, and the miners were trapped, with the entrance sealed shut! Luckily, Eruptor knew just the trick. He ran to the beach and blew the entrance open with a bomb! The tracks the train was on also coincidently went right into the mine! Now, the Fire Skylanders journeyed into the mine to save the moles, and more importantly, get the Crucible!