Tryndamere

Strengths

Delaying the activation of Undying Rage is a very effective way to make an enemy champion over-commit to trying to kill you.
Bloodlust is an excellent way to heal Tryndamere. Try not to let it fade off before you activate it.
If the enemy is stacking Armor, try building items like Last Whisper or Youmuu's Ghostblade.

Passive · Battle Fury — Tryndamere gains Fury for each attack, critical strike, and killing blow he makes. Fury passively increases his Critical Strike Chance and can be consumed with his Bloodlust spell.
Q · Bloodlust — Tryndamere thrives on the thrills of combat, increasing his Attack Damage as he is more and more wounded. He can cast Bloodlust to consume his Fury and heal himself.
W · Mocking Shout — Tryndamere lets out an insulting cry, decreasing surrounding champions' Attack Damage. Enemies with their backs turned to Tryndamere also have their Move Speed reduced.
E · Spinning Slash — Tryndamere slices toward a target unit, dealing damage to enemies in his path.
Ultimate · Undying Rage — Tryndamere's lust for battle becomes so strong that he is unable to die, no matter how wounded he becomes.

A suggested 5-lane lineup built around Tryndamere, based on hero partnerships and role synergy — not win rate.