Tryndamere

Tryndamere is built on one blunt idea: his critical strike chance rises as his health falls. A nearly dead Tryndamere is a Tryndamere at maximum power, which inverts the usual logic of a duel completely.

Undying Rage makes him impossible to kill for a few seconds. It isn't a shield or a damage reduction, it's immunity to death. It turns lost fights into wins, doubles as an escape after taking a tower, and forces the enemy team to play around its cooldown rather than around his health bar.

In a duel, few champions beat him once he has items. Bloodlust returns health on demand, Mocking Shout cuts the attack damage of everyone around him, and Spinning Slash gives him decent mobility to catch a target or cross a wall. He pushes a lane very fast and becomes a nightmare to defend against one on one.

His weaknesses are structural. He brings almost nothing to a team beyond his own damage: no reliable lockdown, no engage, nothing to protect an ally. He leans heavily on critical strike luck early, and a team that controls him properly neutralises him, because being immortal is worthless if you can't move.

Your lane is about banking fury without getting punished. Every critical strike gives you some, and that fury is both your power and your healing reserve. Don't spend it at the first sliver of missing health: save it for the trade that matters, or you'll have no heal exactly when you need one.

Mocking Shout is underrated. Used before a trade, it cuts your opponent's attack damage for the whole duel, which is often enough to flip a losing matchup. And since you're the obvious gank target, play knowing your ultimate is your only answer: spend it on a greedy kill and you're dead to the next gank.

Your first spike arrives with your first critical strike item. The champion lives on crit, and without it your passive never expresses itself: while your base chance is low you're at the mercy of luck, which makes your duels unpredictable.

The second spike is the ultimate, which redefines how you play the map. You can dive under a tower, take the duel you should lose, or walk out of a three-man collapse. The attack speed and lifesteal that follow let you stay in a scrum rather than pass through it.

Your value isn't in the five versus five, it's in the split push. While your team occupies the enemy, you take a tower on the far side of the map. They have to send one or two players to stop you, and that imbalance is exactly what you're after.

When you are forced into a grouped fight, come in from a flank and go for the enemy carry or mage, never the front line. Your ultimate has to be active before the lockdown that kills you, not after: a second late and the immunity is worthless because you're already dead or already held.