Crystal Maiden + Faceless Void

Why this works

Getting caught in a Chronosphere is bad enough, but having a Crystal Maiden on Faceless Void's team makes it much more dangerous. A well-placed Freezing Field on top of the lockdown zone gives Maiden's ultimate the chance to deal its full damage without her being interrupted. It provides a simple but effective plan for teamfights. Outside of their ultimates, Crystal Maiden's Frostbite can hold a target down for Faceless Void to secure a kill in lane or set up his Chronosphere. Her global mana aura also helps him use Time Walk more frequently to farm or escape pressure early on.

This pairing is heavily reliant on their long-cooldown ultimates, so their impact is periodic. Crystal Maiden is also a very fragile hero and a prime target for the enemy team. Opponents will actively try to burst her down before a fight even starts, or use long-range abilities to cancel her Freezing Field from outside the Chronosphere. The entire fight often becomes about whether Faceless Void can land a good ultimate and whether his team can protect Maiden while she channels. If either of those things goes wrong, the plan falls apart completely.