It's been a long time coming, however Valve has now launched the "first-ever cooperative Multiplayer Campaign" for Dota 2. The first act of a proposed two—named The Sands of Fate—is out now and is available for Battle Pass owners, which are charged at £7.99/$9.99.
So far as story is concerned, players are invited to "undertake a secret mission" that sees them tasked with defeating the "fiendish" Siltbreaker antagonist and his followers. In doing so, players stand to earn Artifacts which can be used during the Battle Pass season.
Here's Valve with the skinny:
"As Act I opens, Siltbreaker awakens in the depths of Dark Reef, and the mysterious Conclave of the Brine calls upon you to halt this dark power’s ascent, starting with Siltbreaker’s twisted creation—Rhyzik the Corruptor.
"As you battle through multiple play zones in search of Rhyzik, you’ll earn completion stars based on your performance level. The first time you complete a zone with one or two stars will net you Battle Points rewards, and delivering a three-star zone performance will grant a treasure from Siltbreaker himself."
Valve continues to say players with a Battle Level of 165 or higher stand to land double the treasure in each three-star zone they complete and that "each Siltbreaker Treasure includes a chance to receive an indescribably-rare Immortal Desert Sands Baby Roshan courier."
Dota 2's co-op multiplayer Act 1: The Sands of Fate is out now via Steam.