Bounty Hunter + Pangolier

Why this works

Setting up a clean Rolling Thunder is a bit easier when the target is already under the effects of Track. The vision helps Pangolier aim his ultimate from fog, and the bonus movement speed lets both heroes chase anyone who survives the initial impact. The extra gold from Track kills is also helpful for an item-dependent core like Pangolier, accelerating him toward his first few items. Beyond that, though, their kits don't have a lot of direct overlap. Bounty Hunter provides some initial burst, but he's mostly there to enable Pangolier's initiation and help clean up.

This duo's game plan revolves around creating mid-game pickoffs and snowballing the gold advantage. Bounty Hunter finds a target, Pangolier rolls in for the kill, and the team gets richer. The problem is that their combined impact can fall off if they don't get that early lead. They lack reliable, spammable lockdown for drawn-out fights once Rolling Thunder has been used, and neither hero excels at sieging high ground. If the enemy team can survive the initial ganks and group up, they can often overpower this combo with more traditional teamfight spells.