Sniper + Ursa

Why this works

Enemy teams often find it easy to isolate one of these two heroes in a fight. Ursa is a hero that needs to run directly at the enemy and stay on top of them to be effective. Sniper, by contrast, positions at the extreme back of a fight, needing space and time to deal his damage. While Sniper can offer a slow from Shrapnel, he doesn't provide the hard lockdown Ursa needs to stick to slippery targets. In return, Ursa offers very little protection for Sniper; his entire kit is designed to go forward, leaving his backline exposed.

This creates a teamfight dynamic where the two cores are essentially fighting separate battles. Ursa might be deep in the enemy ranks trying to burst a target, while Sniper is far behind, hitting whoever walks into his range. A coordinated opponent can exploit this gap by either kiting Ursa while a diver eliminates Sniper, or by collapsing on Ursa before Sniper can contribute meaningful damage. Unless one of them is already very far ahead, their conflicting positioning needs make it difficult to execute a cohesive plan.