Bloodseeker + Lifestealer

Why this works

Playing against this pair can feel oppressive once a fight breaks out. Lifestealer wants to get on a target and stay there, and Bloodseeker's kit makes that much easier. A well-placed Rupture can force an enemy to stand still, creating a perfect window for Lifestealer to use Rage and attack freely without being stunned or slowed. Any damage dealt makes enemies bleed, which in turn speeds up Bloodseeker from his Thirst passive. Lifestealer gets an easy target, and Bloodseeker gets the vision and movement speed to clean up or chase down the next one.

The synergy really depends on timing and coordination. During the laning stage, Bloodseeker and Lifestealer are often in different parts of the map, farming their initial items. The combination comes online in the mid-game, once they start moving together to find pickoffs. The main way to handle them is to force fights when their key spells are on cooldown or to disengage and split them up. If you can survive Lifestealer's Rage duration or teleport away from a Rupture, their offensive power drops significantly, leaving you with two melee cores who can be kited.