During the lantern event Leona notices that Malleus turned pottery into ash with his magic, despite not being nearby at the time. Malleus accuses him of spying but Leona says, “The air’s filled with the smell of burnt clay. It’s not hard to connect the dots.”
After losing a koma battle during New Year’s Leona himself is able to evaluate what it is they did wrong (“I took this for a simple kids’ game, but it’s got a surprising amount of depth”).
Leona is shown as the only character suspicious of Silver’s report that he heard Lilia scream at the beginning of Spectral Soiree and he is proven to be correct, with Lilia later revealing he had screamed outside of Silver’s room on purpose in order to reveal himself as the culprit.
When Rook insists on remaining behind with the housewardens and Crowley at the start of the event Leona accurately surmises that Rook has a private observation he wishes to share (Rook: “My mind must be an open book to you”).
During the event Leona notices Ace’s ploy to protect himself while sacrificing Epel, including how and why:
Leona: “You knew Floyd was gonna use someone as bait, didn’t you?”
Ace: “…you were onto me, huh?”
Leona: “You probably thought you’d be safe if you stuck close to me. You made a calculated choice to abandon Epel to his fate and use me as a shield.”
It is also Leona who realizes that the doors leading to the final stage of the Spectral Soiree adventure were specifically designed to only open when the entire group of students was ready to go through: “Which means someone intentionally brought us here at the same time.”
During the group’s battle against Malleus it is Leona who realizes that Malleus is not actually possessed, based entirely upon Leona noticing a slight inconsistency in Malleus’ verbal tic.
Leona is suspicious of Skully early on in the NBC event, questioning if even Skully himself realizes his own dissatisfaction with the situation he finds himself in of his idol rejecting all his ideas and opinions in favor of those of others.
Skully claims he is certain that Jack Skellington has thought deeply about their course of action but Leona says he doubts it, accurately describing Jack as “the kind of guy who gets complete tunnel vision when he gets fixated on somethin’.”
Later Trey wonders why Skully would abduct someone he idolizes and Leona explains, “It’s probably BECAUSE he idolized him.” Malleus says that Skully seemed to accept the opinions of others being prioritized over his own and Leona responds, “It’s easy to say somethin’ without actually meanin’ it. He was pretty defeated back there. Kept sighin’ to himself and everything.”
Leona remains consistently suspicious of Skully’s true identity throughout the event, saying that something feels “off” about their assumption that Skully is from RSA due to “his weirdly skewed knowledge,” namely, how he seems to have never heard of Malleus.
Leona describes Skully as smart, saying there is a possibility that he is lying about where he came from, but he does not know why Skully would have lied to people he only just met. Ultimately Leona is unable to make the connection that Skully himself does, realizing that he is from hundreds of years in the past—possibly predating even Malleus—and dead.
It is Leona who realizes that they have been isekai’d during the NBC event, makes the connection that Sally has poisoned Finkelstein, and notices when Jamil has used his unique magic on Lock, Shock and Barrel.
In the lead-up to the final battle against Malleus Idia summons Riddle to his room for programming support, not Ortho, confusing them both. Ortho asks why Idia would summon Riddle instead of him and Leona explains, “Because you’re supposed to be our nav, of course. We can escape dreams just fine with Silver’s magic, but without you, we’ve got no way of knowing where we’re going. He made a judgement call that wouldn’t leave us up the creek without a paddle.”
When Riddle asks the same question of Idia himself, Idia confirms that Leona’s explanation of the reasoning behind his decision was correct.
Leona seems to realize what Idia means by “extra equipment” in Book 7 before anyone else, saying, “This better not be going where I think it is…”
Idia responds, “There’s just no fooling some people. Sad…”
Twisted Wonderland Reference Note 