Kassadin

Kassadin is the most honest contract on the roster: you agree to lose the early game, and in exchange you get an assassin nobody can escape or stop from starting his sequence. Riftwalk teleports him again and again, Null Sphere silences the one target that could have answered, Force Pulse slows everything caught in the cone, and Nether Blade feeds back the mana his mobility is starving for.

Void Stone makes him a specific nightmare for mages: the more magic damage you throw at him, the faster he swings. Against a physical opponent, though, he's simply a squishy champion with a good escape. This is a curve champion, not a comfort champion. If you don't enjoy farming under your tower while taking a beating, pick something else.

His main strength is structural: his mobility has no real limit, only a mana price that climbs as he chains it. That gives him something no other assassin in the mode has, the certainty of reaching his target and leaving again. Add the silence on Null Sphere, which cuts a channel, a summoner spell or an escape stone dead, and you have a dedicated carry executioner. Void Stone hands him a genuine edge in mage duels on top of that.

The weaknesses before six are brutal. His spells cost a lot, his range is short, his health is low and he has no way to win a lane trade against a mage poking him from distance. After six the problem changes shape: every extra Riftwalk costs more, so a Kassadin out of mana is a Kassadin with no exit. And he deals no area damage at all, so against a tightly grouped composition he barely exists.

Your goal before level six isn't to win, it's to reach level six on even minions. Max Null Sphere first: it's your ranged last hit and your safety button when a jungler shows up. Never throw it away as free poke, your mana pool won't carry it and you'll end up silent at exactly the wrong moment.

Use Nether Blade to pick up the minions you can't reach otherwise. Its passive returns mana on every attack, and considerably more when you land one on a champion, which is your only real sustain in lane. Force Pulse only charges from spells cast around you, so in a quiet lane you simply won't have it and you shouldn't build a plan around it. Stay behind the wave, keep the river warded, and let the lane push toward you.

Level six is the sharpest swing in the mode. You go from a champion who absorbs to a champion who decides: you can leave lane without being followed, arrive on someone who thought they were out of reach, and walk into the enemy jungle knowing you'll walk back out. It's also the moment your lane opponent suddenly has to buy vision and play scared.

The second real spike is your first completed power item paired with your mana pool. Kassadin only becomes a kill threat once he can chain several Riftwalks and land a sequence that finishes a target in one go. Levels eleven and sixteen matter as much as items: the shorter Riftwalk cooldown changes your movement rhythm more than any purchase does.

You never open. You wait until the enemy front line has spent its crowd control, then you cross over for the carry, silence first to cut off their answer. A Kassadin who enters alongside his own tank dies having achieved nothing. A Kassadin who enters three seconds later wins the fight by himself.

Watch your mana bar like a second health bar. The classic trap is spending two Riftwalks to get in and having nothing left to get out. Always count one exit blink before committing. Against a team that stays tightly packed, don't force anything: play the flanks, catch someone isolated before they group, and push a sidelane nobody can contest, since you're the hardest player on the map to pin down.