Skywrath Mage + Ursa

Why this works

Picking off heroes with this duo often proves unreliable, which slows down the whole game plan. Ursa needs a partner with a hard stun or root to hold a target in place for his Overpower and Fury Swipes. Skywrath Mage brings a slow from Concussive Shot and a silence from Ancient Seal, but no way to truly lock someone down. This gives enemies a window to use items or movement spells to get away before Ursa can secure the kill. Both heroes want to unload their full damage combo on a stationary target, but neither can provide the setup for the other.

This inability to guarantee kills makes it difficult for Ursa to hit his timings for Roshan and other key objectives. If the ganks aren't converting into gold, Ursa is forced into a slower farm pattern that he doesn't excel at. Enemy teams can anticipate the gank attempts and build defensive items like Force Staff, which counter both heroes effectively. Later in the game, the lineup lacks the teamfight control needed to deal with multiple threats. Skywrath gets focused down easily, and Ursa finds himself kited, leaving both unable to contribute their massive damage when it counts.