Nyx Assassin + Phoenix

Why this works

Trying to focus down Phoenix's Supernova is a nightmare when Nyx Assassin is nearby. Any hero committing to hit the egg has to worry about an Impale from the side, stunning them and their allies. Even if they get close, a well-timed Spiked Carapace from Nyx will stun the single hardest-hitting enemy, often buying enough time for the egg to explode. This combination of multi-hero and single-target lockdown makes it incredibly difficult to prevent the reset and massive stun that Supernova provides. Phoenix is free to play aggressively, knowing that Nyx provides the perfect insurance policy for his ultimate.

This strength defines teamfights from the mid-game onward. The enemy is forced to either save their stuns and burst for Nyx Assassin before he can react, or they have to try and split their damage between him and the egg, which rarely works. Earlier in the game, Phoenix's Fire Spirits provide a reliable slow to set up easy ganks for a roaming Nyx. The constant threat of a Vendetta strike followed by Phoenix's full spell combo creates pressure across the entire map, forcing opponents to play defensively and clump up, which only makes Supernova stronger.