Grimstroke + Snapfire

Why this works

Landing Soulbind on two heroes creates an almost guaranteed kill with Snapfire nearby. Her Mortimer Kisses deals a huge amount of damage in an area, and since the bound targets can't separate, they both have to endure the full volley. The slows from the globs make escaping impossible. Even outside of that combo, Snapfire's stuns and slows make it incredibly easy for Grimstroke to land his own spells like Stroke of Fate and Phantom's Embrace. The whole laning phase is a constant chain of lockdown and damage that wears opponents down.

This forces the enemy team to play spread out from the mid-game onwards. Grouping for towers or Roshan is a massive risk when a single Grimstroke ultimate can set up a team wipe. The constant threat forces them to buy specific items to break the tether or to try and find a pick-off on either Grimstroke or Snapfire before a fight can begin. It puts a ton of pressure on their positioning and coordination, often forcing mistakes that this duo is perfectly equipped to punish.