Phantom Assassin + Windranger

Why this works

Trying to set up a kill for Phantom Assassin often relies entirely on Windranger landing a good Shackleshot. The issue is that both heroes largely do the same thing: apply immense single-target physical damage to a locked-down enemy. Phantom Assassin brings a slow with Stifling Dagger, but she really wants a guaranteed stun to commit with Phantom Strike and her crits. Windranger can provide that, but her stun is one of the least reliable in the game. Their kits don't really offer each other something new so much as they double down on the same plan.

This makes your teamfights very high-variance. A long-duration Shackleshot can hand PA a free kill and win the engagement, but a miss can leave both heroes feeling a bit useless and out of position. It puts a ton of pressure on the Windranger to perform. As a result, the rest of your draft is often forced to compensate by picking heroes with the reliable lockdown and area control that this pair lacks. The duo doesn't actively work against itself, but it creates a narrow and predictable game plan that is easy to punish.