Earthshaker + Magnus

Why this works

Picking these two heroes together commits your draft heavily to one big teamfight plan. Both Magnus and Earthshaker want to be the primary initiator with a Blink Dagger and a huge area-of-effect ultimate. While Reverse Polarity sets up Echo Slam perfectly, having both on one team creates a lot of role overlap. They both want to do the same job at the same time. This can lead to one hero holding their spells waiting for the other, or committing two massive ultimates to a single fight, which is often overkill and leaves you with nothing for a long time afterward.

The main challenge with this duo is surviving until both heroes have their core items. Their laning phases can be fragile, and falling behind makes it difficult to get the Blink Daggers needed to execute the combo. A coordinated enemy team will recognize your strategy and can counter it by playing spread out to minimize the impact of Reverse Polarity and Echo Slam. Even if the big combo works, the opponent has a large window to act while both heroes' ultimates are on cooldown, which can be exploited to take objectives or win the next engagement.