Finishing Move: After Eriko develops a particularly devastating move, Aurora warns her to only use them when absolutely necessary, for fear her enemies will reverse-engineer her techniques.
Forged by the Gods: Aurora crafted the Golden Knife, and it took her over a year to enchant it, at least part of which was ensuring it would work on worlds faerie magic was denied.
For Science!: The reason Eriko considers looking for the island of stability physicists are trying to discover with particle accelerators is as simple as that. Not just for herself, she supplies some research labs with magically created Unbihexium.
Genre Savvy: Eriko most certainly is. But instead of following anime tropes, she acts based on what's known to work in reality. Sometimes overt pragmatism does come to bite her back, reminding her to think outside the box - and this is when genre tropes come in handy.
Muggle Born of Mages: Spirits have no bodies: when they want one, they whip up a human body with whatever cosmetic alterations they want. These bodies are capable of reproducing ... resulting in non-magical humans, which the faeries call faeborn.
Multiversal Conqueror: the four main multiverse factions (faeries, demons, elysians and the Circle) fall into this. Universes that gain magic become accessible and a new battleground.
Person of Mass Destruction: Every mage is theoretically capable of this, in a variety of ways. Monsoon uses the example of a mage on an alternate Earth who conjured up some antimatter - "Only a little. Just enough to fill a crate."
Playing Both Sides: Victoria Steel provides anti-mage weapons to Japan in exchange for money and information to Downfall in exchange for magic.
Ray Gun: The PRISMs (Paranormal Risk Incineration SysteM) fall into this: industrial laser technology applied to breaking through a mage's kinetic shields. They're about the size of a car, but effective.
Starter Villain: Downfall. He starts out slightly stronger than Soul but doesn't level up any between their first and final encounters (while she advances considerably) and is well below-par at planning and scheming. The other villains play him like a fiddle.
Lampshaded, to the point of having the in-universe version of TV Tropes add an example to its Real Life section.
The Watson: Junko. Secano. Hiromasa. And arguably others.
Try to Fit That on a Business Card: Exalted Grand Adviser Chancell, master of House Lor. Hero to the Elysium thrice. Imperial Mastermind. Recipient of the Supreme One's Trust. Recipient of the Supreme One's Greater Trust. Recipient of the Supreme One's Perfect Trust. Resident of the Domain of Wonders. Key Holder of the Domain of Wonders.
He keeps trying to convince them to only announce the highest level of Trust and not bother with "Resident" when it's made superfluous by "Key Holder," but it's a slow process. Maybe in another couple centuries.
Thinking Up Portals: Eriko uses them several impressive ways, such as weaponizing seawater through pressure and the Earth's rotation.
Wake Up, Go to School, Save the World: Eriko often has to respond to the Soul-Signal while in class. In at least one case, her enemies time an attack to shortly after class starts to ensure she's late to the scene.