Dawnbreaker + Necrophos

Why this works

Securing a kill on a key hero and turning it into an objective is the whole point. Necrophos is great at finding a target for Reaper's Scythe, but he often needs help surviving the attempt or cleaning up afterwards. Dawnbreaker provides that backup from anywhere on the map with Solar Guardian. She can land right as the Scythe connects, guaranteeing the kill and immediately starting a new fight on favorable terms with her stun and AoE heal. It turns what looks like a solo pick-off into a full team engagement you weren't prepared for.

This global threat completely changes how the enemy has to play. They can't show heroes with low health anywhere, because a Necrophos ultimate could mean a Dawnbreaker arrival a few seconds later. The counter-play involves either bursting Necrophos down so fast that the combo never happens, or having enough lockdown to interrupt Solar Guardian's landing. For their part, the pair wants to force this scenario over and over, using the pressure to take towers and control territory the enemy is too afraid to contest alone.