The more I think about Earthspark Season 4 the more I believe the Blades of Time could have worked as a final villain weapon.
Okay, so if we've got a weapon that deletes your memories and sets you back to being evil well, introduce that at the start of the story. Not the last ten minutes.
But like, if the story had started off with the Bots and Cons are finally getting on and rebuilding things (like they should have been doing the whole time!) but the suddenly the Cons go evil and everyone is shocked and surprised by what's happening. How their friends/mentors betray them?
Then one of the Terrans notices something, like a Con says some sort of banter thing during a battle and they realise they don't seem to have any memories of who they are. That's when you can have Optimus pull his Matrix knowledge to tell them about some sacred, long thought lost weapon. They discover about Liege Maximo, go to confront him and Oh No! He hits Megatron with the Blades and now Megatron is a bad guy all again, and he leads this newly turned Decepticon army on Liege's behalf. Cliffhanger.
Next part is entirely about fighting these evil Decepticons and trying to bring them back to their former selves.
We could have something like Twitch gets captured and she keeps occasionally talking to him and trying to tell him about the current life he leads, but he continuously dismisses it.
Also since Megs has gone back to his old self he's back to ruling with fear and intimidation. And starts being horrible to Starscream again. At one point Megs is about to hit Starscream but Hashtag steps in his way to stop him, and this jogs Starscream's memories and he goes back to his real self. Though maybe he initially tries to hide that fact from Megs so he can stay close to Liege Maximo and observe what he's doing. But slowly they start thinking of ways they can revive the Deceptions and bring them back.
I also think it might have been stronger if the final threat was Unicron rather than Liege (though you could also have Liege working for Unicron). Make it so Unicron is manipulating everyone to this because he wants there to only be fighting and chaos. Neverending hatred benefits him, and the only way to defeat him is by embracing our differences and finding love for everyone. That's now something that fits in with the themes that were present in Season 1. Make Unicron a metaphor for divisive hate.
But either way, it ends happily with everyone back to their proper selves and establishing peace. I feel we definitely deserved an ending like that over the ending we got.