Star accepts an invitation from her ex-boyfriend Tom to Demon Prom. Marco, suspicious of Tom's intentions, crashes the prom to prevent Star from getting her heart broken again.
Tropes:
- All Girls Want Bad Boys: Played with. While Tom is a Chick Magnet, Star makes it clear she doesn't want to be with him because of his temper. He has to display his bunny and anger management guy to convince her to come to the dance. As she makes clear to Marco, she's only going to see if he has changed for real.
- Ambiguous Situation: It's never made clear whether the Blood Moon really does have the ability to bond souls together, and even then it's never said if the bond has to be romantic (though that mysterious voice did say "the moon of lovers"). Also, while Star is clearly enjoying herself when she starts dancing with a supposed stranger, it's hard to read Marco's reaction to dancing with Star, as his mask is covering his eyebrows and mouth.
- Anti-Climax: Tom getting absolutely furious at Marco for stealing his dance with Star is hyped with very impressive pyrotechnics and ominous music, promising an epic showdown... and then Star just encases him in a block of ice, before walking out.
- Appeal to Flattery: In the original storyboard, Tom gets Star to go to the dance with him by saying she's been nominated for Demon Prom Queen.
- Attention Deficit... Ooh, Shiny!: Immediately after agreeing to keep standing where she is, Star wanders off staring up at where the moon is shining.
- Bad Moon Rising: The Blood Moon Ball gets its name from the red crescent moon shining onto it. The moon itself isn't a bad omen, though Tom trying to abuse it for his own purposes is.
- Bait-and-Switch: Star says "So infuriating" after she and Marco come back from the ball. Marco replies that he tried to warn her about Tom, but it's him she's angry at, since he didn't trust her to handle it.
- Be Careful What You Wish For: Marco begs Star repeatedly to spend time with him instead of Tom, since she's more likely to have fun with him than with her ex. Come the end of the episode, he gets his wish, at the cost of making Star angry at him for not trusting her judgment.
- Brick Joke: Marco eats nachos as Comfort Food after Star leaves for the dance. After Star chews him out for not trusting her judgment, she demands that he make her nachos.
- Call-Back:
- Star brings up the fact that her best friend is a unicorn head when Tom wants to go through the traditional ritual of having unicorn blood poured onto them.
- The voice that warns Marco about Tom sounds suspiciously like Monster Arm.
- Cephalothorax: One party guest, who complains to Star that Tom has made the ball boring to please her, is a big head with arms and legs.
- Chick Magnet: All the girls in Echo Creek Academy appear to be rather taken with Tom's hammy entrance.
- Comfort Food: Marco is shown eating nachos and listening to a "Dia de los Muertos" mix-tape after Star leaves to go for the ball over his protests.
- Compliment Backfire: "Star Butterfly, don't you clean up nicely." Star gives an awkward thanks in response.
- Control Freak: Tom, Tom, Tom. He redesigns the Blood Moon Ball to make it more sanitized for Star, informs other ball-goers that her "dance card is full" to ensure that the Blood Moon binds him and Star for eternity, and insists on getting his choice of music for their first dance. This last one dooms him, as Marco sneaks in and unintentionally steals the dance while Tom is busy.
- Curb-Stomp Battle: Star versus Tom, when Tom nearly kills Marco at the ball. He's frozen solid with one shot.
- Damsel out of Distress: Star gets annoyed by Marco's attempts to "rescue" her, since she's very much capable of curb-stomping Tom the moment he loses his anger.
- Dance of Romance: The Blood Moon Ball's special feature is that two attendants will be chosen to dance under the light of the Blood Moon, binding their souls together. Tom was trying to rig things so he and Star would be chosen, but Marco accidentally takes his place after a mysterious voice urges him to crash the party. Star is clearly smitten with her mysterious partner too, at least before Marco reveals himself under his mask.
- Deus ex Machina: If not for the disembodied voice urging Marco to go to the ball, Tom may have succeeded with his plan.
- Did Not Think This Through: Actually averted; Star does think through the ramifications of going on one date with Tom to see if he's changed. She points out to Marco that it's better to know for certain, that maybe she'll actually have fun even if the night goes nowhere and that sooner or later she has to be able to make decisions without his help. During the dance, she deflects Tom's attempts to douse her in unicorn blood or change her hair tie, and curb-stomps him when he threatens Marco.
- Digging Yourself Deeper: Tom after wanting to get dunked in unicorn blood. When Star points out that her best friend is a unicorn, he says "they're probably not related" and after she refuses, realizes that he brought his bunny and anger-management counselor and is on the verge of losing his temper. Fortunately for Tom, Star decides to give him a few minutes to cool down and get herself a drink.
- Does This Remind You of Anything?: One of the demons at the ball describes how a lucky couple chosen by the blood moon will have their souls joined forever, but the way he intertwines his fingers as a visual aid makes it sound like another way a couple is "joined" together.
- The Dog Was the Mastermind: The mysterious voice that tells Marco to head to the ball (which leads to Tom's plans being ruined) turns out to have been the portrait of the old sea captain in Star's bedroom, according to
Word of God. - Everyone Has Standards: Even a delinquent like Oskar would never park in a handicapped spot.
- Everything's Better With Bunnies: Tom brings an adorable bunny (named Marshmallow, according to Word of God) in a bid to convince Star he's changed.
- Exorcist Head: Hilariously inverted. Tom holds his head in place so he can continue to give Marco a Death Glare while he and his anger-management counselor "walk it out" in a circle.
- Extra Digits: One bat-like fellow at the party has hands sporting six digits. It especially stands out since the art style otherwise uses Four-Fingered Hands.
- Game Face: Tom's face and eyes become monstrous when he's angry.
- Glowing Eyes of Doom: Tom's eyes turn blood red when he's mad.
- Green-Eyed Monster: Averted on Marco's part. He doesn't mind that another guy is taking out Star on a date, and he is supportive of her getting together with Oskar, but with Tom he's worried that the latter will break Star's heart again. The only "envy" part is that Star would turn down a guaranteed night of fun with him in favor of risking time with Tom.
- Hair-Trigger Temper: The littlest things make Tom angry, from Star refusing to wear a hair tie he provides her to the DJ playing the wrong music. His anger counselor has to be on the job 24/7, it seems.
- Hearing Voices: A voice from nowhere (apparently the sea captain portrait) compels Marco to go to the ball.
- He Is Not My Boyfriend: Averted; despite Marco attacking Tom, mistaking him for a monster, Marco and Star don't invoke this. It helps that before Tom can barbecue Marco for chopping his hand off, the anger management coach helps him walk in circles to calm down. Ironically, Tom and Star don't notice that Tom parked his car next to Oskar, and Oskar is Star's actual crush.
- Hidden Depths: As Star lampshades, Marco turns out to be a pretty good dancer.
- Human Popsicle: Star freezes Tom in a block of ice just before he attacks Marco.
- I'll Be in My Bunk: "I'll have my own Blood Moon Ball… in Star's bedroom… where it's always fun."
- Loves My Alter Ego: A very brief example. Star is clearly smitten with Marco in disguise during their dance, only to snap out of it when he surprises her by revealing himself.
- Mood Whiplash: When Tom loses his chance to be declared Star's soulmate by the Blood Moon, he gets very mad, with not even his coach being able to calm him down, and his intent to kill Marco becomes obvious. Then Star just freezes Tom, and changes his pin to say he's been anger-free for 0 days.
- "No Peeking!" Request: Star tells Marco not to peek while she's changing into a formal dress for the Blood Moon Ball.
- Nothing Is Scarier: A mysterious, disembodied voice compels Marco to go to the ball. What is that voice? The episode doesn't even drop a single hint about it, other than it vaguely sounded like the Monster Arm. According to Daron Nefcy, the voice came from the portrait of the sea captain in Star's room.
- Not What It Looks Like: Marco attacks Tom, mistaking him for the many monsters that target Star for her wand. This is quite understandable given Marco has been assigned as Star's guide and she appears to be in danger. Star then has to explain that it's "Tom, demon ex-boyfriend Tom". Even so, Marco maintains a protective stance.
- Number of the Beast: Subverted; according to Tom, the Blood Moon Ball only comes once every 667 years.
- Ominous Pipe Organ: It plays throughout the episode. Tom gets annoyed when the organist starts playing a sombre piece instead of the dance that he wanted.
- One True Love: Rather heavily implied in this episode. A mysterious voice prods Marco into going to the Blood Moon Ball which causes him and Star to have their souls bonded under the blood moon's light.
- Playing with Fire: Tom has fiery footsteps, and other flame related powers.
- Poke the Poodle: Tom takes up the handicap spot with his skeleton-pulled carriage from Hell.
- Rage Breaking Point: Tom spends the episode getting annoyed when something doesn't goes his way, but keeps his temper under control with some effort. But when Star and Marco end up doing the Dance of Romance, all bets are off and Hell (literally!) breaks loose."That dance. Was meant. FOR ME!!"
- Razor-Sharp Hand: Marco slices off Tom's hand with a karate chop.
- Red String of Fate: Legend goes that two souls are bound together if they dance under the blood moon. Exploiting this is why Tom invited Star to the ball; he wanted her to dance with the devil in the blood moon light. That said, she ends up dancing with Marco.
- She Cleans Up Nicely: While Star is by no means bad to look at, there is a noticeable difference from how she normally is to what she looks like dressed for the prom. Marco says she looks "amazing" and Tom quotes this trope.
- Ship Tease: The two souls who dance under the light of the blood moon will be bound together for life. Guess who ends up dancing under the blood moon? Star and Marco, that's who. This either this cements their status as best friends forever or something more romantic.
- Spanner in the Works: Marco didn't know about Tom's plan to dance with Star under the blood moon, but that didn't stop him from stealing the dance and binding his soul to Star's instead.
- Speak in Unison: Star and Marco indulge in a bit of this near the end of the episode, adding to the Ship Tease factor (and hinting that "the bonding of two souls" thing might not be just a romantic metaphor).
- Stupid Sexy Friend: Marco gets rather embarrassed when he catches a glimpse of Star's bare leg while she's changing into her ball gown.
- Tame His Anger: Tom's has been attempting this by hiring a life coach and having a bunny to pet when he's angry. He snaps when he sees Marco dancing with Star under the blood moon, wrecking his only chance to bind Star's soul to his.
- Theme Park Version: One of the demons complains to Star that Tom has done this to Hell to make her happy.
- Tomato in the Mirror: The skeleton horse didn't realize he was dead until being told.
- Unwanted Rescue: Star is angry at Marco for rescuing her because it means he didn't trust her judgement.
- What Does She See in Him?: Marco views Star's ex-boyfriend as a predator and doesn't understand why she is still willing to go to the Blood Moon Ball with him when they broke up before.
- What the Fu Are You Doing?: In the original storyboard version, Marco tries to do "Praying Mantis" style, complete with Funny Bruce Lee Noises. Star politely asks him to stop.
- What the Hell, Hero?: While Star appreciates Marco wanting to help, she's angry that he didn't trust her to be able to handle Tom on her own.
- X Days Since: Tom wears a button that says he's been anger free for 53 days. After Star freezes him for getting mad, she also changes it to read "0 Days Anger Free".
