Spectre + Zeus

Why this works

Picking someone off across the map becomes a simple two-button job. Zeus provides global vision and damage with Thundergod's Wrath, showing Spectre exactly who is low and where they are. This removes all the guesswork from Haunt. Instead of jumping in blind, Spectre gets a perfect menu of vulnerable targets to choose from. The initial magic burst from Zeus means that by the time Spectre arrives with her illusion, the enemy is already in kill range. It's a huge amount of damage from two different heroes, appearing on a target with no warning.

This constant threat completely changes how the other team has to play the game. Spreading out to farm or push lanes becomes a huge risk, as any isolated hero is a potential kill for the Spectre and Zeus combo. This forces opponents to group up earlier than they'd like, ceding map control and letting Spectre farm more safely. Their only real choice is to try and five-man push to end the game, but even that plays into the duo's hands, as a big teamfight ultimate from Zeus sets Spectre up to clean house.