Ogre Magi + Witch Doctor

Why this works

Setting up for a kill becomes much more reliable with this pair. Ogre Magi offers a simple, point-and-click stun with Fireblast that gives Witch Doctor the perfect opening to land his abilities. A guaranteed stun makes it easy to follow up with Paralyzing Cask and Maledict, ensuring the target takes amplified damage. Most importantly, it holds an enemy in place for the full duration of a Death Ward channel. Bloodlust is a nice bonus for a core attacking the same target, but the core of the synergy is Ogre providing the reliable lockdown that Witch Doctor needs to secure kills with his ultimate.

This dynamic gives the lane a lot of early kill threat, as a stun from either hero can lead to a kill. As the game progresses, your team's plan often boils down to Ogre finding an initiation with Fireblast so Witch Doctor can delete a key target. The reason this isn't a stronger combination is that the setup is fairly straightforward and single-target. Aware opponents will look for ways to interrupt the Death Ward channel or build defensive items to survive the initial stun. It gives your team a clear game plan, but it's a plan that can be played around.