How to counter Chaos Knight

In lane

Enigma
• Chaos Knight has no way to deal with Demonic Summoning. • Midnight Pulse deals a lot of damage to Chaos Knight and his illusions. • Black Hole usually will catch Chaos Knight with all his illusions since Reality Rift pulls all of them to the target.

Naga Siren
• She can disjoint Chaos Bolt with Mirror Image. • Rip Tide shreds his illusions. • Chaos Knight's damage and spells are all single-target, making him weaker against illusion heroes.
Winter Wyvern
• Chaos Knight is usually grouped with his illusions, meaning Winter's Curse can delete a nearby ally or the main hero. • Cold Embrace is a good save against the physical damage of Chaos Knight.
Timbersaw
• Chaos Knight has high strength gain, so Whirling Death is very effective. • All of Timbersaw's spells are great at killing his illusions. • Reactive Armor provides high armor which is great against illusions. • Phantasm's attacks are counted 4x for Reactive Armor stacks.
Sand King
• The overwhelming damage of Sand King's spells is a great way to deal with illusions. • Caustic Finale makes the illusions explode on death, dealing damage.

Shiva's Guard
• This item provides armor and slows down the movement and attack speed of the illusions, while also dealing damage.
Ghost Scepter
• Turning ethereal can be a good save against this hero.