Bounty Hunter + Pudge

Why this works

Placing Track on an enemy gives Pudge the vision he needs to line up a long-range Meat Hook. Bounty Hunter can scout from invisibility to find these opportunities, making Pudge's positioning for a gank much easier. If Pudge misses the hook but can get close, a Jinada strike from Bounty Hunter can slow the target enough for Rot to wear them down. The core of this partnership rests on Pudge landing a key skillshot, which isn't always guaranteed and keeps the combination from being a consistent lockdown.

This duo wants to run around the map securing kills from the early game onward. The gold from successful ganks with Track helps Pudge hit his item timings and maintain pressure. The problem is that both heroes are focused on single-target burst. When opponents begin to group up for teamfights, the impact of a single hook and a Track kill diminishes. Lacking significant wave clear or area-of-effect damage, they can find themselves unable to crack high ground or defend against a coordinated push if their early-game snowball doesn't create a big enough lead.