Here is how The Predacon's plot, Quickstrike attacks and Yuna's Sacrifice goes in The Journey Back to Life Part 1.
Meanwhile, Megatron and his Predacons were working on an evil plan.
Megatron: I swear, If I haven't promised any of my Predacons that I wouldn't kill you, I would've killed you!
Quickstrike: I just thought that I can you my tail for the good killin'.
Megatron: Silence! I don't want to hear another word about your plans. Am I understood? Yes!
Quickstrike: But, How could I answer/ You said not another word.
In rage, Megatron angrily slams another Predacon onto the wall.
Megatron: Very well, Quickstrike. Do as you must to be rid of anypony!
Quickstrike: Awe, Thanks, Boss. I won't fail you!
Megatron: I certainly hope not!
Prince Edmond: Well, It sure brings back the good old days. This is so much fun.
La Muerte: Edmond, Have I told you about when you were a baby colt?
Prince Edmond: I don't recall.
La Muerte: I was your godmother long ago.
Prince Edmond: Really, La Muerte?
La Muerte: Yes, And you were such an adorable colt.
Prince Edmond: No kidding.
La Muerte: I have to go now, I got work to do in The Land of the Remembered. (teleported away)
Prince Edmond: See ya.
Just then, Quickstrike appears.
Quickstrike: Well, well, well.
Golden Scissor: Uh oh!
Bronze Bracelet: It's Quickstrike!
Turbo: We have to get everyone out of here!
Quickstrike: Yee-Haw! (spotted Snowdrop) Well, Lookie here!
Snowdrop: Oh my! Who's there!
Nyx: Oh no! He's going after Snowdrop!
Quickstrike: Just one poison sting from my Cobra Whip!
Princess Yuna: Snowdrop!
Quickstrike: (As the teeth stabs Yuna in her back)
Princess Yuna: AAAAAAHHHH!!!!! NOOOOOOOOOOOO!!!!!!
Quickstrike: You're so weak! So long, Little Lady! (shoots Yuna with his whip)
Titanic: Princess Yuna!
Quickstrike: (pulls the Cobra Whip out of Yuna's back)
Princess Yuna: (falls to the ground)
Princess Luna: Yuna!
Princess Yuna: (her eyes were closed)
Princess Luna: No! Yuna! (sobbed)
Human Rarity: (fainted)
Turbo: (as Sheen Estevez) NOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO!!!!!!!!!!!!!
Airazor: Oh no! We're too late!
Tigatron: No! Yuna!
Titanic II: She did what she could to save Snowdrop.
Princess Luna: I didn't want it to end like this!
Britannic: Princess Yuna's sacrifice for Princess Snowdrop will never be forgotten.
Princess Luna: I can't believe I've lost my own first born.
Princess Celestia: No! Yuna! My brave brave niece. (sheds her tear)
Prince Isamu: (cried)
Princess Luna: (sobs)
Prince Indy and Princess Anna: (cried)
Round Up: Mama, Is she...?
Starla: (in pony form) Yes, Round Up. She's gone.
Britannic: Come, We must give her a fair burial.