Seven Deadly Sins & Elizabeth Liones vs. Demon King

Seven Deadly Sins & Elizabeth Liones vs. Demon King is a battle between the Seven Deadly Sins and Elizabeth Liones against the Demon King.

Prologue
To save Zeldris from the Demon King, Meliodas and Elizabeth rush to Lake Salisbury, where the Demon King is. Meliodas deduces his father chose there as to recover the magic he spent fighting the Sins back at Camelot and to fully assimilate with Zeldris' body as quickly as possible to avoid being driven out again.

Elizabeth sees Meliodas' reluctance but assures him that Zeldris is waiting for him and he tries to agree as he thinks back to when their relationship soured after failing to get his brother to come with him, but he ultimately refused out of fear of their father and because of Gelda's condition.

On their way, the Demon King already realizes Meliodas and Elizabeth are on their way and mockingly states how Zeldris will help him get revenge on his "foolish older brother". Within the mindscape, Zeldris awakes and realizes that Cusack forced him to absorbed the Commandments and that his father had possessed his body and demands for him to leave as he still had unfinished business, to which a voice calls out to him and he is shocked to see the form of Gelda, but immediately realizes his father created her to trick him.

The false Gelda, however, tricks him by telling how Meliodas killed her twelve years ago and tricked him into getting the Commandments for him, to his rage. She also explains how the Demon King has approved their relationship and Zeldris gives into this false hope, relieving the Demon King of him attempting to take back control just as Meliodas and Elizabeth both appear and land on the opposite side of the lake.

Battle
Due to Meliodas having reached the same level of power as his father, the mortal plane begins to react violently due to there being two Demon Kings and upsetting the balance between light and darkness. The Demon King further confirms this but Meliodas counters by saying the world does not need any god ruling over it to begin with, claiming every tragedy for the past 3,000 years was because the Demon King and Supreme Deity constantly clashed due to their bitter rivalry.