Dark Seer + Necrophos

Why this works

Pushing lanes together can give this pairing some decent map control. Dark Seer can place Ion Shell on Necrophos, who is already naturally durable and can sustain himself with Death Pulse. This turns Necrophos into a walking hazard who can shove waves and pressure towers, forcing enemy reactions. Surge is also useful for helping the otherwise slow Necrophos get into the middle of a fight or chase down a low-health target. A good Vacuum can group enemies, amplifying the damage from Heartstopper Aura and setting up a multi-hero Death Pulse.

The effectiveness of this duo is very conditional, though. Both heroes lack reliable stuns, so enemies with mobility or saves can often escape a Vacuum combo before Necrophos secures a kill. If the enemy team is good at splitting up and kiting, the slow-moving deathball of Dark Seer and Necrophos can struggle to accomplish anything. Without a strong early lead, they can also find themselves competing for the same areas of farm, which slows down their key item timings and leaves them vulnerable.