Veigar vs Locke

Last-hit minions with Baleful Strike (Q): each kill with this spell gives you a Phenomenal Evil stack, which is power for the whole game, and large minions give more.

Place Event Horizon (E) so your target is on the edge or has to cross it: only the cage's perimeter stuns, and it only lasts 3 seconds.

Stun first with Event Horizon (E), then cast Dark Matter (W): a stunned target can't dodge it.

Cast Primordial Burst (R) last, after your other spells: its damage rises with the target's missing health and peaks below 33%.

Back instead of staying in lane at low health: Silver Stake (passive) adds damage to his autos that grows with your missing health.

Trade after Ashen Pursuit (E): it's his only instant movement, and its 10-second cooldown only resets if he gets a takedown.

During Soul Ignition (W), only hit him if you can kill him: at the end, he heals back part of the last damage taken, yours included.

Marked by Purgatory (R), stay above its threshold: if you have a heal or a shield, use it, because he seals marked enemies who drop below it.

If the Purgatory (R) artifact lands, hold the area where it fell: by picking it up, Locke raises his execute threshold for each sealed champion, for the rest of the game.