"Alrighty, the key should be here somewhere." T-Bone said as the five of them descended deeper into the Underworld. "Don't worry, fellas. I won't run out on you this time. Just be sure ya don't run out to far ahead, or else…" Suddenly, a huge wall closed and separated T-Bone from the Undead Skylanders! "…we might get separated. Huh, guess I'll just wait out here, then." As the four continued forward, then eventually found themselves in a room filled with zombies, more specifically, Rotting Robbies! "Muhhhhhhh…" The reanimated corpses shuffled towards their prey. Acting quickly, Chop Chop lit his sword ablaze via candle and swung it, catching one zombie on fire! He then spotted a cannon, which he then lit with his blazing blade, with the fire about to die out. One big boom later, and the area was zombie-free. In the next area, the four encountered a pack of Rhu-Babies, accompanied with an Undead Spell Punk. Once only a few Rhu-Babies were left, the spell punk worked his magic. Then, after chants and growth, the Rhu-Baby had become a massive Rhu-Barb! Seeing the beast almost unstoppable, Cynder then figured it all out. She then blasted the spell punk with lightning, defeating it and causing the monster to shrink and become defeated as well. Then, Chop Chop used his shield to block arrows coming from skeletal archers: Bone 'n' Arrows which emerged from the coffins against the walls in the form of a pile of bones which then formed the threat, while Hex used her magic to stop some in mid-air. After a long trek, the Skeleton Key was found at last! The four then brought it back to T-Bone. "Nice!" He said. "This'll open the gate to the Creepy Citadel! AND it also does this!" He then plucked his head off and screwed it onto the key. "Amazing, huh? Comes in pretty handy looking through keyholes!" And with that, they went to the staircase to descend even deeper into the Underworld, and into the Creepy Citadel to retrieve the Eternal Undead Source.