Get Hearthstone's Curse of Naxxramas add-on for $25 or $20 or with gold or — well, it's confusing

Blizzard’s Hearthstone: Heroes of Warcraft collectible card game has focused so far on pitting players against one another in free-to-play online battles, but it’s about to expand into a single-player adventure — as long as you can pay the entry fee.

We’ve known that Hearthstone’s first major expansion, Curse of Naxxramas, was coming this summer for quite some time, but Blizzard is finally detailing how you can buy it. The developer plans to dole out each part of the five-section dungeon one week at a time. The good news is that the first “wing” of the dungeon, Arachnid Quarter, is free during Hearthstone’s Curse of Naxxramas launch event. Blizzard says it plans to run that event for a month.