Reign of the Black Empire went live on 20 October 2026 with 135 new collectible cards, the four Old Gods at the height of their power, the new Assemble keyword and the Titan-forged who fight them (Reign of the Black Empire Is Now Live!). This guide sets out what mattered in the first week, with Blizzard’s article behind each part.
The Old Gods: one per deck
C’Thun, Eye of the Empire, N’Zoth, Dream’s End, Mastermind Yogg-Saron and Y’Shaarj, Titan Bane are Legendary Neutral minions, and a deck may hold only one of them. Each has four abilities: instead of attacking, an Old God invokes two of them each turn, and once all four are spent it is free to attack (Command the Old Gods in Reign of the Black Empire). C’Thun rewards triggering its abilities early with cards such as Spawn of C’Thun; N’Zoth builds on Deathrattles; Yogg-Saron takes a whole extra turn for you; Y’Shaarj wants big minions and a survived early game.
Assemble and the Titan-forged
Assemble adds a minion to your hand and replaces part of its card text with the text of another minion from a curated pool, so the same card can be built for different decks. The Titan-forged side includes Isiset, a Mage Legendary whose Battlecry summons two 10/10 Constructs that stay Frozen until you have spent 15 mana on spells (Command the Old Gods).
Free cards and packs to collect
- M.O.T.H.E.R. was free with Patch 36.6, and Arrival of the Old Gods, Arrival of the Titans and Dark Terraforming were earned free through the events before launch (Command the Old Gods).
- Journey, in the new Journal, started on 13 October with Chapter 1: The Road to Ny’alotha: seven parts over seven weeks, one Reign of the Black Empire pack for each part you complete, and earlier parts stay open until Patch 38.0 (Embark on Your Hearthstone Journey).
- The launch event runs from 20 October to 10 November: Event Quests and Event XP pay five Reign of the Black Empire packs, five Escape from Violet Hold packs, two Golden Escape from Violet Hold packs and the Ritual N’Zoth hero skin for Warlock (37.0 Patch Notes).
- Every Tuesday at 10:00 a.m. PDT the Battle.net Shop has a free weekly reward to claim (37.0 Patch Notes).
Decks and Arena
Every class gained a new Deck Recipe built around Reign of the Black Empire cards, beside a Core deck and an Escape from Violet Hold deck. Arena started a new season on 13 October with the new cards in its pool a week early; Underground’s 12-win reward is now the Il’gynoth hero skin for Demon Hunter, and from 20 October Arena and Underground pack rewards are Reign of the Black Empire packs (37.0 Patch Notes).
After the first week
Blizzard first used temporary bans on a few early outliers, then made permanent changes in Patch 37.0.2 on 3 November: C’Thun, Eye of the Empire had emerged as the strongest Old God, so its early activators were weakened and C’Thun itself now quadruples its abilities instead of tripling them; Warlock combos with M.O.T.H.E.R., Bat Mask and Divergence were toned down and M.O.T.H.E.R. now costs 10 mana (37.0.2 Patch Notes). Next on the calendar is the 30 Years of Terror event with Diablo, from 10 November to 1 December (37.0 Patch Notes).
Sources: Blizzard’s official Hearthstone news, linked in each part above.