Saving energy and spell cooldowns until you use your ultimate will maximize Death Mark's damage.
Quickly double tapping Living Shadow will teleport Zed to his shadow immediately for rapid escapes.
Placing a Living Shadow before using Death Mark can give Zed a safe escape from combat.
Zed receives bonus effect from Attack Damage items he purchases, so Armor is super effective against him.
After Zed uses his Living Shadow, he is at his most vulnerable as his damage, slow, and mobility are both dependent upon it.
Zed's Shadow Slash can only slow you if his shadow hits you with it.