Lich + Spirit Breaker

Why this works

Setting up a good Chain Frost can be tricky, but Spirit Breaker makes it simple. His Charge of Darkness provides a long-duration stun from anywhere on the map, giving Lich all the time he needs to position and land his ultimate on a held-down target. The combination of Frost Blast's slow and the initial stun makes it almost impossible for the primary target to escape, and very likely that the ultimate will bounce to any nearby allies who try to help. Lich essentially gets a perfect setup for his most powerful spell, over and over.

This creates a powerful pick-off combination that comes online early and stays relevant. Spirit Breaker can initiate on isolated heroes, and with a Frost Shield on him, he's surprisingly tough to burst down when he arrives. Lich provides the magical damage needed to finish the job. The opposing team is forced to play uncomfortably close together to avoid giving Lich's ultimate ideal bounces, which in turn makes them vulnerable to other area-of-effect spells. Trying to split the map and farm becomes extremely dangerous against this duo's global pressure.