Faceless Void + Zeus

Why this works

Setting up a Chronosphere gives Zeus a perfect window to land his damage. Enemies caught by Faceless Void are sitting ducks for Thundergod's Wrath, which can be cast from anywhere on the map to contribute to a kill. This makes for reliable long-range pickoffs. If Zeus is closer to the fight, he can unload his entire arsenal on the frozen targets for a massive amount of magical burst. The vision from Lightning Bolt can also be useful for scouting a target for Void to jump on, preventing escapes into the trees.

This combo is defined by its long ultimate cooldowns. The team plays around these abilities being ready, creating a major power spike for key teamfights or Roshan attempts. Once those spells are used, the synergy is gone for a while, and the enemy will look to press their advantage. Experienced opponents will also prioritize items that mitigate magic damage, like a Pipe of Insight or Black King Bars for their cores. This forces Faceless Void to do most of the killing on his own and dampens the overall impact of the combination in later fights.