When Bald Mountain village got sucked away into Kingdom hearts, Chernabog was dragged with it into the World that Never Was, where he confronted his once most promising pupil, Master Xehanort, and berated him for betraying him in order to fulfill the Great Cycle instead of freeing him from Bald Mountain. In anger, Chernabog used his dark magic to clothe himself once more as the World of Chaos, Abaddon, and attacked Master Xehanort and his forces. But by this point, Master Xehanort's power had increased to be on the same level as the dark lord himself, and was able to defeat the monster and seal away his evil consciousness within his keyblade.
But now there was a new problem. Chernabog's mindless body was now rioting on a rampage, without a clear conscience to properly control it. thanks to Xehanort's Heartless, the mindless monster was easily tamed. Soon afterwards, Abaddon became the main enforcer of the world that never was, and the last to be fought litterally as our heroes got to the front gates of the castle after beating the other forces of the Great Cycle, Abaddon was right there waiting to be fought. Thankfully, Sora, Master Yen Sid, and King Mickey were able to summon their keyblades and defeated the monster, knocking it into a deep near-death slumber. Afterwards, our heroes marched upward and confronted Master Xehanort.
when everything returned to normal, Chernabog found himself in his prison on Bald Mountain again, and he silently cursed his luck with an angry growl.