The entire opening. It builds suspense pretty well. Then when the entire cave starts shaking, it gets really intense really fast.
Bowser survives the earthquake, but is then taunted by something swiping back and forth out of frame. He's one step from the exit, before the Goomba comes rocketing at him! He screams as it grows closer and closer...! Then it cuts to black. What a way to open, ironically, one of the more lighthearted Mushroom Parodies.
The opening is also pretty scary. Two friends are just walking together, before one of them is suddenly hit with a flying book and thrown to the ground! His friend rushes over to help him, and looks up to see the very ghost that just maimed his friend is floating towards them. Then it goes straight to opening credits.
The scene where Devil shows up in Luigi's house is nothing short of chilling. It opens with Luigi tossing and turning in bed as thunder booms in the distance. He mutters in his sleep as the storm rages outside. Cut to a wide shot of the room, and that same thunder flashes to show the literal Devil. He's watching Luigias he sleeps.
Then, Luigi wakes up in a strange room. Confused, he looks up to see that same Devil. He has a monologue he disguises under the veil of being Affably Evil to trick Luigi into a false sense of security before he asks Luigi to pick one person he respects more than anyone else. He picks his brother, Mario. Then, Devil suddenly becomes sinister and knocks Mario off the platform they're standing on. Luigi furiously asks "how could you" before Devil reveals his real plan: to twist this figure that Luigi idolizes and make him fight it.
