Spectre + Tinker

Why this works

Picking off an isolated hero becomes the core game plan. Spectre can Haunt onto a target anywhere, and if there's a creep wave or friendly unit nearby, Tinker can teleport in to add a massive burst of magic damage with Laser and Heat-Seeking Missile. This global ganking potential is potent; Spectre's Desolate damage shines when the target is alone, and Tinker's Laser can blind a core trying to fight back. Tinker can also apply Defense Matrix to Spectre, making her much harder to burst down when she jumps into the fight.

The success of this pairing comes down to a race. Tinker excels at pushing out all three lanes, creating the map-wide space that Spectre needs to farm her core items without interruption. The tradeoff is that the team becomes extremely greedy and lacks early-game fighting power and lockdown. If the enemy team is built to apply pressure early, they can often run over your lanes and take objectives before either Spectre or Tinker are ready to fight. The game hinges on whether your team can survive long enough for this space-creation engine to pay off.