Enchantress + Faceless Void

Why this works

Being trapped in a Chronosphere is bad enough, but having an Enchantress hitting you from a safe distance makes it much worse. Faceless Void provides a perfect, stationary target for her Impetus. Because she can stand far outside the bubble, she can maximize her pure damage output on a key enemy without any risk of being caught herself. While other heroes might be frozen, Enchantress is free to unload her attacks, which can be enough to burst down a durable target who might otherwise have survived the duration of Void’s ultimate. The setup is simple and effective for deleting one specific hero.

This entire dynamic, however, relies on a well-placed Chronosphere. If Faceless Void catches the wrong target or misses key enemies, Enchantress’s single-target damage doesn't do much to turn the tide. As the game progresses, a farmed Void often has enough damage to solo-kill his targets anyway, making her contribution less critical. While her Untouchable slow and healing can help keep Void alive outside of his ultimate, the main synergy is very cooldown-dependent. It's a nice bonus for picking off a priority hero, but it doesn't fundamentally change how either hero wants to play the game.