Even though she owes nothing to, and doesn't even particularly like, Imori, Stella still takes the risk to extract his soul from the Dragon Prison and return him to life.
Should you care? Imori's an asshole. Couldn't take no for an answer. A hundred people die every minute. Thousands, millions, of people are suffering every day. What's one more? But... What's one less?
While acting as a playtester for an allegedly new card, Stella is forced to duel an initiate of the Doma cult. Her opponent continuously brags throughout their duel about the number of people he's killed and how she's going to be his seventeenth victim that night. Stella remains entirely unimpressed throughout Caleb's tirade, questions him one last time on the lives he's stolen and, when he rebukes her while stating that his power gives him the right to do as he pleases, disrupts her opponent's entire field and playstyle by using his newly acquired power against him.
"I did nothing wrong!" He shouts, pointing at you. "I earned those victories! I earned this power! You don't get to judge me, none of you trash do! Don't act like you're better than me! You're just some little girl-" "I activate the Field Spell, Seal of Orichalcos." "Don't you- Huh?"
In her third duel in the Duelist Kingdom Tournament, Stella matches Bandit Keith blow for blow throughout their battle, destroying the former U.S. champion's Barrel Dragon first with Magician of Black Chaos, then again by destroying the Call of the Haunted used to resurrect it. She then manages to firmly seize the advantage by summoning a Mystic Plasma Zone empowered Beast of Talwar, keeps said advantage by attacking Keith's facedown Blast Sphere with her Archfiend Heiress, and, after stopping each of Keith's plays cold, finally seizes the victory by summoning Hamon and using both of her Beasts to wipe out Keith's last monster along with the rest of his Life Points.
While no other contestant seen was able to put up a decent fight against Mai Valentine, Stella forces the Harpy duelist on to the back foot right from the beginning, using her Mystical Space Typhoon to destroy Mai's Mirror Wall, then Hymn of Light to stop her Fearsome Fireblast, and then launching an all out assault with both Saffira and Chakra that forces Mai to desperately stall for time before inevitably losing to Stella's overwhelming offensive.
When Camula reveals herself to Stella, they make a point of talking down to their opponent, stating that Stella was merely a placeholder for Hamon who's purpose has come to an end now that she's arrived to claim it for her own. Stella decides to prove exactly how worthy she is by destroying her opponent's backrow, subverting Camula's only monster with Brain Control, then attacking directly with both Manju and Chakra to deliver the first OTK in the entire quest, all to the tune of her Leitmotif, Final Answer.
Stella:I am not a placeholder. I am not a weak little girl. I have a place in this world, Camula, and you will not take it from me.
vs. Para & Dox
At the start of the duel, Stella sent her Manju and Saffira down separate paths of the Labyrinth with Saffira taking the more direct route to destroy the Paradox Brother's Different Dimension Capsule and Manju taking the shortest route available to the opponent's gate. The two brothers initially prioritize protecting their capsule and destroying Saffira. Not only do both initiatives fail due to Stella's Mystical Space Typhoon and Skull Dice, they also allow Manju to make it almost the entire way across the board which gives Stella the chance to summon her Magician only four spaces from her opponent's gate.
After Stella seizes control of their Suijin, Para and Dox attempt to put a halt to Magician's movement through Shadow Spell. Unfortunately for them, Duelist Kingdom rules are still in play even with the Labyrinth on the field and the spell of shadows proves entirely ineffectual against the Magician of Black Chaos. With their last line of defense shattered, the brothers are left helpless and are immediately defeated by Stella's strongest monster.
vs Bandit Keith, Round 2
Keith has significantly improved his deck since the last time he faced Stella, using a large number of LP gaining cards such as Draining Shield and Enchanted Javelin to boost his Life Points while bringing Stella's offensive charge to a screeching halt. He then reveals the reason for his new traps; Keith is in possession of one of the world's only copies of Cyber Stein and uses it to bring out Cyber Ogre #2.
Stella expends her once-per-duel Destiny Draw to dispose of Keith's Ogre, but Keith still manages to stall long enough to draw into the materials needed for his arguably stronger Gatling Dragon with said monster's effect allowing it to effectively clear Stella's board after only two turns.
With no cards on her field, her soul and Shadow Charm on the line, and only 1050 Life Points left, Stella forces herself to keep her composure, sets Sonic Duck on the field and a card in her backrow, and bluffs. Keith knows that Stella fields Mystic Tomato, and that no spell or trap ever printed will be able to stop his Dragon's effect, so he sets an additional monster as collateral and lets loose the Steel Rain. This is exactly the play Stella was hoping for as she activates the set Destruction Jammer she recently acquired from Meisei to destroy Keith's dragon.
Stella manages to predict the usage of each of Keith's Blast Sphere and doesn't once fall for them, attacking the first one with Rogue Doll to preserve her life points and prevent Keith from completely clearing her board, and attacking the second only after she has Dark Sacrifice ready to defuse the bomb.
After every one of Keith's plans has failed and he's left with an empty board and only 200 Life Points left, the former number one decides to pull a gun on his opponent. This only hastens his defeat as Keith's actions allow Stella to enact a Penalty Game wherein the surrounding Shadows converge upon Bandit Keith and rip his soul from his body.
.Stella: I am not a placeholder. I am not a weak little girl. I have a place in this world, Camula, and you will not take it from me.