In “American Dad!: Dungeons and Wagons”, "Rothaga" is actually "Agathor" - Steve's name spelled backwards.
It was Klaus' suggestion, so Hayley can have Jeff back. Steve's Avatar can be destroyed by saying 'Agathor' backwards, which is 'Rohtaga'. This is most probably a reference to Superman antagonist Mr. Mxyzptlk, who can only be defeated by having his name said backwards.
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Of interest, Den of Geek shares The 10 Best American Dad Episodes.