- The infamous "White Devil" scene at the end of Episode 8. What started off as a simple, typical Training Montage suddenly turns to horror when someone so innocent like Nanoha brutally injures Teana. Even Subaru is horrified by this.
- The following episode reveals that at one point in Nanoha's career, she suffered injuries so severe it almost ended her career as a mage and threatened to cripple her for life.◊ The look of horror on the forwards' faces as Shamal showed them the extent of Nanoha's injury was pretty understandable.
- Episode 17. ALL of it.
- Any scene involving Quattro and Dr. Scaglietti, especially in the case of Quattro, who enjoys torturing Vivio.
- Episode 18. Vivio is Strapped to an Operating Table, feebly struggles, and screams for Nanoha as Scaglietti talks about how she's going to be his masterpiece. And, as Quattro points out, Vivio knows exactly what they're planning to do to her. As it cuts away to outside the room, we hear Vivio scream "Mama!" one last time before the episode ends.
- The end of episode 19, when Vivio is powering the Saint's Cradle. Even worse, Nanoha is watching the whole thing via broadcast and can't do anything about it.Vivio: It hurts! I'm scared! Mama, Mama!
Nightmare Fuel / Magical Girl Lyrical Nanoha StrikerS