Phoenix + Riki

Why this works

Fighting inside Riki's Smoke Screen is already a problem, but adding Phoenix makes it nearly impossible. The silence prevents enemies from using spells to stop Phoenix's Sun Ray or to escape its slowing beam. This gives Phoenix a free window to commit Supernova on top of everyone. While enemies are slowed, silenced, and missing attacks, they can't effectively focus the egg. Riki also gets to freely attack targets who are unable to cast anything back at him, all while they're being melted by Fire Spirits and the main beam.

This combination comes online very early since Smoke Screen is a basic ability, making the pair a threat long before many lineups hit their stride. They can dominate fights by forcing opponents into a terrible choice: try to kill the Supernova egg while silenced, or run away and give up the objective. The enemy team has to play spread out and invest in detection and items that can purge the silence. Phoenix and Riki, meanwhile, will look for any chance to fight in a chokepoint where their combo is guaranteed to catch multiple heroes.