Bane + Faceless Void

Why this works

Stacking control during teamfights is the main idea here. Faceless Void can lock down a group of enemies in Chronosphere, and Bane follows up by using Fiend's Grip on the most dangerous target inside. This is especially useful for burning through a Black King Bar or neutralizing a hero with strong defensive abilities that might otherwise survive the Chronosphere's duration. Nightmare also provides a long-duration, reliable setup, allowing Void to perfectly position a Chronosphere for a guaranteed pick-off on an isolated hero.

The problem is that this combination of ultimates is often either overkill or not enough. If Void is farmed, he can typically kill the targets in his Chronosphere without help, making Bane's contribution redundant. If the team is behind, using two of your biggest spells to kill one or two heroes might not be enough to win the fight. There's also a natural timing conflict: Bane creates pressure from the start, while Void needs time to farm his core items. This can lead to games where their plans don't line up, making the synergy feel inconsistent.