Defeat Black Doom

Duck is running after that Battle

Duck: (Panting) How come? It was mine.

?????: Know this. The heart that is strong and true shall win the sword.

Duck: Huh? Are you saying that my heart's is weaker than his?

?????: For that instant, it was. However, you can become stronger. You showed no fear in stepping through the door to darkness. It helps no terror for you. Plunge deeper into the darkness, and you heart will grow even stronger.

Duck: How can I do that?

?????: It's really quite Simple. Open yourself to the darkness. That is all. Let your heart, your being, become darkness itself.

1 hour later

Duck walked up to Black Doom

Duck: So, I see the path has emerge at last.

Black Doom: Yes. The Symbol of Darkness.

Duck: Take it and the Heartless will overrun this world.

Black Doom: What do I care? The darkness holds no power over me. Rather, I will use it's power to rule all worlds.

Duck: Such confidence.

He Summon a Sword that has Black Blade in it

Black Doom: Impressive. Wait a minute. The Symbol is not Finished! The Princesses of Hearts are all here. It must be her.

They look at Lexi lifeless Body

Duck: Without her heart, she will never be able to release her power.

And they heard a noise

Black Doom: That bunny's fools are here. I'll take care of them. You stay here and look after the Princesses.

Duck body is Glowing blue

Back to our Heroes

They found Black Doom waiting for them

Black Doom: I think that you are too late. Any moment now, the final Symbol will never be taken. This world will be plunged into darkness. It is unstoppable.

Ace: We'll get it! After coming this far, there's no way we're gonna give up that easily!

Black Doom: You imbecile Fools! You think you could defeat me? Me, the Overlord of Evil?

They are fighting him and they defeated him and he went to the Portal and our Heroes is following him

Black Doom: (Panting)

Then Duck has comes out of the Portal

Duck: Do you need some help?

Ace: Duck!

They saw a Sword that Duck is holding

Daffy: Was that...

Duck: Yes. A Sword. Unlike yours, this sword will unlock the People Heart. Allow me to demonstrate.

He aim his Sword to Black Doom's Chest

Duck: Behold!

Black Doom: What- are you- doing?!

Duck: Now open your heart. Surrounded to the darkness. Become Darkness Itself.

He went to the Portal and then Black Doom is Glowing

Black Doom: This is it! This Power! (Laugh) Darkness! The True Darkness!

He became a Monster and they Fighting him and he has been Defeated

Duck: How Ironic. So he was another puppet after all.

Daffy: What are you talking about?

Duck: The Heartless are using Black Doom from the Beginning. He failed to notice the darkness in his heart eating away at him. A fitting for such a fool.

He went to the Portal