What it does
Magician has one trigger: use a move that hits an opponent while you're holding no item, and you steal their held item. The stolen item stays with you for the rest of the match.
The constraints matter. You can't activate it if you're already holding something — so you enter battle itemless. The item transfers from opponent to you; they lose it entirely. If they aren't holding an item, nothing happens.
The value scales with what you steal. A Choice Scarf gives you a 1.5× speed boost while stripping the opponent's speed advantage. Choice Specs hands you 1.5× Special Attack. Choice Band gives physical firepower. Stealing any of these is a free swing in your favor that also cripples the opponent.
Who runs it
Delphox (47%): Fire/Psychic, and it runs Magician by entering without an item, then hitting a Choice item holder. Fire Blast or Psyshock land the move and trigger the steal simultaneously. Priority target: Choice Scarf users, because taking their Scarf immediately flips the Speed comparison — you speed up, they slow down. If Delphox snags Choice Specs, its Special Attack punches noticeably harder from that point on.
Klefki (0%): Essentially never runs Magician competitively — Klefki's value comes from other things entirely.
How to use it
Delphox enters without a held item. You need to land a damaging move on a target that has something worth taking. The most valuable targets are Choice item holders — they're common enough that you'll find opportunities.
The key risk: your opponent can predict the steal and switch out. Magician requires hitting the active Pokémon, and switching avoids it. If they go out the back door, you've spent your attack for nothing. This is an ability that rewards not telegraphing your intent.
Tips & strategy
Magician is a bluff game. Experienced opponents will assume you're hunting for their Choice item and rotate it away the moment Delphox comes in. The window where this is effective is when they don't realize you're going to steal — first turn in, before they've identified your game plan.
What you steal also matters. Berries and recovery items are nearly worthless on Delphox. If you hit a Pokémon holding a Lum Berry, congratulations — now you have a Lum Berry you can't use effectively. Target Choice items and you're getting something genuinely impactful. Take anything else and the ability may as well not have fired.