Grimstroke + Lifestealer

Why this works

Trying to run from an enraged Lifestealer is already difficult, but with Grimstroke on his team it's often impossible. Ink Swell provides a large AoE stun that Lifestealer can deliver safely while magic immune, guaranteeing a strong initiation. Later on, Grimstroke's Soulbind makes teamfighting a nightmare for the opposition. A single-target lockdown item from Lifestealer, like an Abyssal Blade, will hit both leashed heroes, creating massive control. Grimstroke can follow up with his own spells like Phantom's Embrace to silence and damage both targets while they're held down.

This pairing comes online early and scales well. Mid-game ganks are brutally effective using the "Infest bomb" combo: Lifestealer hides inside a unit, Grimstroke channels Ink Swell on him, and they run at a target for a guaranteed stun and kill. Against this, the enemy team is forced to play spread out to avoid getting caught by a multi-hero Soulbind. Their main hope is to either burst Grimstroke before he can cast his ultimate or survive Lifestealer's Rage duration and try to kite him afterward, which is difficult when Grimstroke provides so many slows.