Phantom Lancer + Slardar

Why this works

Controlling the mid-game with pickoffs becomes a lot more reliable. Slardar's Corrosive Haze makes a single target extremely vulnerable to physical attacks, which is exactly what Phantom Lancer and his illusions provide. A simple Slithereen Crush can hold someone in place long enough for PL to close the distance and surround them. The armor reduction amplifies the damage from every single illusion, letting the pair burst down even durable heroes much earlier than Phantom Lancer could on his own. This pressure helps create space for PL to farm his core items safely.

This duo excels at turning a successful gank into an objective like Roshan or a tower. Slardar leads the charge, and Phantom Lancer follows up to secure the kill. The main counter-play for opponents is to simply group up, as the armor reduction only applies to one hero. Teams with strong area-of-effect spells can also quickly clear out the illusions, making the bonus damage from Corrosive Haze irrelevant. The combo helps get Phantom Lancer ahead, but it doesn't solve his core vulnerability to big teamfight ultimates.