Katarina

Katarina spends neither mana nor energy. She's limited only by cooldowns, and her passive cuts them sharply on every kill or assist. She's the one champion on the roster who literally speeds up as a fight goes her way.

Shunpo blinks her to a target, friend or enemy, and reduces the damage she takes afterwards. It's her entry, her escape and her repositioning tool all at once. Played well, she crosses an entire scrum hopping from target to target. Played badly, she lands in the middle of five enemies and dies in a second.

Her ability to chain is unique. A single kill brings her whole kit back, and a team that collapses hands her a chain reaction nobody can stop halfway. Death Lotus hits several targets at once, which makes her one of the few assassins genuinely dangerous in a grouped fight rather than on an isolated pick.

Her weakness is brutal and singular: she depends entirely on a channelled ultimate. Any stun, any silence, any forced displacement interrupts it and deletes half her damage. She's also extremely fragile, and a badly chosen entry cannot be walked back.

Bouncing Blades is your only safe pressure: throw it at the wave so it bounces onto the enemy champion. It costs you nothing and lets you harass without ever stepping up.

Resist offensive Shunpo until you have your ultimate. Blinking in to land Sinister Steel puts you in range of their whole kit with nothing to finish with. Keep Shunpo as an exit: it also targets a minion or a ward, which gets you over a wall and out of a gank. You are everyone's favourite jungle target, so ward early.

Your ultimate changes everything. Before it you're a mediocre poke mage. After it you have a window where a squishy target dies, and that window opens others through your passive.

After that, raw ability power matters more than penetration early, because your problem isn't cutting through resistances, it's killing fast enough for the channel to finish. An item that returns health while you channel changes the nature of the champion: you go from an assassin who enters and dies to one who enters and stays.

You never enter first. Wait until the enemy's crowd control has been spent on someone else, then choose your entry point. Shunpo can target a ward placed on the flank, which is the clean way to arrive behind their line rather than in the middle of it.

Once you commit, the ultimate needs to hit several targets to be worth its cost. Position between two enemies rather than on one. And keep track at all times of who on their side can interrupt you: that person, not the carry, decides whether your fight happens at all.