Doom + Luna

Why this works

Casting the Doom ultimate on an enemy hero creates a problem for Luna. Her Eclipse deals its damage by hitting random enemies in an area, but a Doomed target is already completely neutralized. Any beams from her ultimate that strike this disabled hero are effectively wasted, as that damage could have been used on another enemy who is still a threat. This lack of coordination between their main teamfight abilities means they don't amplify each other's impact. Instead of one hero setting up the other, they can end up overlapping in a way that reduces their total combined output in a fight.

Beyond that core interaction, both heroes can be greedy. A team with both a farming Doom and a Luna carry can feel passive in the early game, potentially giving up too much map control before they're ready to fight. While Luna wants to group up and push towers in the mid-game, Doom sometimes prefers to play for a solo pick-off on an isolated target. Their preferred game plans don't always line up, which can lead to awkward moments where the team isn't playing together towards a single objective, making it harder to build a lead.