Beastmaster + Terrorblade

Why this works

Pairing these two heroes forces a difficult choice about the team's entire game plan. Beastmaster hits his peak in the mid-game, wanting to group up, use Primal Roar on a target, and take objectives with his summons. The attack speed from Inner Beast is meant to help knock down towers quickly. However, Terrorblade is one of the slowest carries to come online. He needs extended, safe farm and is often not ready to join these crucial early fights, even if Metamorphosis is available. The core timings of the two heroes are simply at odds with each other.

This results in Beastmaster often trying to force plays with a team that isn't at full strength. His attempts to pressure the map can leave Terrorblade isolated and vulnerable to ganks. The enemy team can capitalize on this split, either picking off the farming carry or winning four-versus-five engagements against the rest of the team. For this lineup to work, the supports have to create an immense amount of space for an extended period, hoping the game doesn't end before Terrorblade gets his core items and can finally use the aura.