Trundle vs Irelia

Start your trades with Chomp (Q): the empowered auto slows your target, then steals some of their attack damage, which matters most against a physical damage dealer.

Take your trades near the wave: King's Tribute (passive) heals you for part of the max health of each enemy that dies near you, minions included.

Place Frozen Domain (W) where the fight will happen and draw the enemy into it: inside, you gain move speed, attack speed and increased healing.

Place Pillar of Ice (E) behind the fleeing enemy: it blocks their path and slows nearby enemies.

Cast Subjugate (R) on the enemy tank: you steal part of their armor and magic resist, and your team can focus them down.

Don't stand near your low-health minions: Bladesurge (Q) resets when it kills, so she chains dashes from minion to minion until she reaches you.

As soon as the first blade of Flawless Duet (E) lands, change direction: the stun only hits enemies caught between the two blades.

Take your trades when Ionian Fervor (passive) isn't stacked: she builds stacks with her abilities, and at max stacks her autos deal more damage.

Save your burst for after Defiant Dance (W): while charging, she takes much less damage, but she can't do anything else.

Dodge Vanguard's Edge (R): its blades make you Unsteady, which resets Bladesurge (Q) on you, and the cage they form damages and slows anyone who crosses it.