Chaos Knight + Magnus

Why this works

Empowering the main Chaos Knight gives him a helpful farming tool and some extra damage, but the cleave from it does not transfer to his Phantasm illusions. They do benefit from the bonus damage, which is nice, but the dream of five heroes cleaving through a whole team doesn't happen. The synergy then mostly comes down to setting up single-target burst. Magnus can use Reverse Polarity to group enemies and lock down a primary target, or Skewer someone important back into CK's grasp. It’s a classic setup, but the follow-up remains focused on one hero at a time.

This makes their game plan very straightforward and sometimes predictable. The duo relies heavily on Magnus landing a good Reverse Polarity to isolate a victim for Chaos Knight and his illusions to swarm. If that initial burst fails or the enemy team has ways to save their caught teammate, the fight can turn quickly. Lacking reliable area damage outside of Magnus’s ultimate, they can struggle against lineups that spread out or have their own summons to bog down the illusions. It's a plan that can certainly delete a key target, but it doesn't always translate into a won teamfight.