Shadow Fiend + Void Spirit

Why this works

Picking both these heroes often creates a role conflict. Shadow Fiend and Void Spirit are both classic mid laners who thrive on hitting a level and item timing to control the game with magic burst. Their kits don't naturally set each other up well. Void Spirit's Aether Remnant can group enemies for a moment, but it’s not the reliable lockdown Shadow Fiend needs to guarantee his Shadowrazes or a point-blank Requiem of Souls. Both heroes are designed to be the primary damage dealer in a fight, not the one creating the opening.

This usually forces one of them into a side lane where they can be less effective. As the game progresses, they often find themselves wanting the same farm on the map to build similar items. In teamfights, their plans can collide rather than combine; they both want to be the one to jump on a vulnerable backliner. Success depends on getting so far ahead that your sheer amount of damage overwhelms the enemy, but if you fall behind, the draft lacks the hard control or utility needed for a comeback.