Malzahar vs Locke

Avoid free damage to keep Void Shift (passive) up: when you haven't taken damage or CC for a while, you take much less damage and ignore CC.

Push the wave with Malefic Visions (E): they finish off low minions, then jump to the nearest enemy when their target dies, restoring your mana.

Cast your other spells, Malefic Visions (E) included, before Void Swarm (W): each one adds a Voidling, and they go after the targets of your visions.

Save Nether Grasp (R) for the enemy carry: you lock them down while you channel, and the zone around them also damages their allies.

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.