This is how The Overlord's return goes in My Little Pony Transformers Prime: Twilight's Kingdom.
[Rare Find is walking through Canterlot when he bumps into a blue misty creature with red eyes and tentacles for legs]
Rare Find: Are you friend or foe?
The Overlord: "Is he friend or is he foe?", the pony wonders. I can assure you... I am no friend. I am the Overlord, and I will take what should have been mine long ago.
[The Overlord sucks out Rare Find's magic using his tentacles. Rare Find's eyes lose their color and his Cutie Mark vanishes and he falls to the ground as the Overlord laughs evilly]
[Princess Celestia wakes up]
Princess Celestia: [gasps]
Princess Luna: Sister, are you alright?!
Princess Celestia: I've just had the most terrible dream.
Princess Luna: Why do you think I'm here? You know as well as I that this was not a dream, but a vision.
Princess Celestia: Then we haven't much time. The stronger he becomes, the more we are all in danger.
[We see a book and the pages open to a picture of the Overlord]
Princess Celestia: [narrating] The Overlord came here from a distant land called Ninjago, intent on stealing Equestrian magic. But a certain Green Ninja, named Lloyd Garmadon, was not having it.
Princess Luna: [narrating] Lloyd urged the Overlord to stop his actions. When the Overlord refused, Lloyd had no choice but to battle him.
Princess Celestia: [narrating] Lloyd prevailed and the Overlord was sent to Tartarus for his crimes. But it appears he has found a way to escape.
Princess Luna: We believe it happened when Cerberus ran off.
Twilight Sparkle: But that was a long time ago. Why is he just now starting to steal magic?
Princess Celestia: His time in Tartarus left him very weak. He has just now gained enough strength to use his dark powers.
Princess Luna: But with each passing moment, he grows stronger still.
Princess Cadance: And I know just the princess who can stop him.
Twilight Sparkle: Yes. I'll find him and–
Princess Celestia: No, Twilight. I'm afraid I must call in another to stop the Overlord.
Twilight Sparkle: What?
Princess Celestia: Discord.
Twilight Sparkle, Princess Luna, Princess Cadance: [gasps]