This is how Thunderwing plans to render the Elements of Harmony useless goes in The Return of Thunderwing.
[Thunderwing is in his lair thinking of a plan]
Thunderwing: I need to do something to render the Elements of Harmony forever useless.
[Thunderwing decides to look through Twilight's memories]
Thunderwing: There must be something in here to turn Twilight against her friends.
[Thunderwing then comes across Twilight's most painful memory]
Thunderwing: What's this?
[Thunderwing decides to play the memory]
Twilight Sparkle: I'm here! I'm not gonna stand next to her! And neither should you!
Shining Armor: I'm sorry, I... I don't know why she's acting like this.
Queen Chrysalis disguise as Princess Cadance: Maybe we should just ignore her.
Twilight Sparkle: You have to listen to me!
Fluttershy: Oh, goodness! Are you okay?
Twilight Sparkle: I'm fine.
Applejack: Ya sure about that?
Twilight Sparkle: I've got something to say! She's evil!
Rest of main cast: [concerned chattering]
Royal guard: [inaudible comment to other guard]
Twilight Sparkle: She's been horrible to my friends, she's obviously done something to her bridesmaids, and if that wasn't enough, I saw her put a spell on my brother that made his eyes go all [bells jangling]!
Queen Chrysalis disguise as Princess Cadance: [starts crying] Why are you doing this to me?!
Twilight Sparkle: Because you're evil!
Queen Chrysalis disguise as Princess Cadance: [crying]
Twilight Sparkle: Evil! And if I don't stop you, you're gonna ruin my brother's life!
Shining Armor: You want to know why my eyes went all [bells jangling]? Nuh! Because ever since I started having to perform my protection spell, I've been getting terrible migraines. Cadance hasn't been casting spells on me. She's been using her magic to heal me!
Twilight Sparkle: [inhales]
Shining Armor: And she decided to replace her bridesmaids because she found out the only reason they wanted to be in the wedding was so that they could meet Canterlot royalty! And if she hasn't been on her best behavior with your [stomps hoof] friends, it's because with me being so busy, she's had to make all the decisions about the wedding!
Twilight Sparkle: I was just trying to–
Shining Armor: She's been completely stressed out because it's really important to her that our big day be perfect! Something that obviously wasn't important to you!
Twilighg Sparkle: [gasps]
Shining Armor: Now if you'll excuse me, I have to go and comfort my bride. And you can forget about being my best mare. In fact, if I were you, I wouldn't show up to the wedding at all.
Applejack: C'mon, y'all. Let's go check on the princess.
Twilight Sparkle: I was–
Princess Celestia: You have a lot to think about.