Earthshaker + Tidehunter

Why this works

Setting up a big teamfight often involves one massive ultimate, but this pair brings two. Tidehunter's Ravage provides a huge, reliable area stun that perfectly sets up for Earthshaker to land a devastating Echo Slam. The chainstun is difficult for enemies to escape, and a follow-up Fissure can lock down anyone who survives the initial blast or tries to flee. The armor reduction from Gush also amplifies the physical damage from both Echo Slam and Earthshaker's Enchant Totem hits on key targets caught in the chaos, making it easier to clean up.

The main issue is that both Ravage and Echo Slam are game-winning abilities on their own. Committing both to a single engagement can be overkill, and it leaves the team without a major teamfight cooldown for a long time. Earthshaker and Tidehunter both want to be the primary Blink Dagger initiator, so they can feel redundant. While the combination is powerful when a fight absolutely must be won, in many scenarios one ultimate would have been sufficient. This overlap in roles means the pairing doesn't consistently produce better results than having two heroes with more distinct jobs.