Board Thread:Spoilers!/@comment-25375217-20160418024756

Just speculation on how Hades could be defeated. You don't have to provide any proof or connections, rampant speculation is totally cool :P

I think that he'll be defeated by turning hopeful and cheery. The entire Underworld becomes bright and friendly with him as its happy-go-lucky ruler, and everyone in the river of lost souls is recovered. This could be accomplished with Zelena kissing him, but I dunno, since he seems to want his heart back but doesn't want hope. Either way though, I think this would be a nice way to defeat him and also keep death from being ruined - no one would want to save their loved ones because they know the Underworld is a happy place and that Hades will help them get to Mount Olympus. Also, having gloom-and-doom no-hope Hades become happy-go-lucky seems like a reversal/defeat that Once would do. 