Players won’t be able to summon the Ancient One directly; instead, players can summon Blood of the Ancient One, a pricey-but-reasonable 9/9 minion for 9 mana. Finish a turn with two of them under your control, and they automatically merge and summon up the Ancient One itself. The result is a minion that’s going to take some work to summon and lacks in special abilities, but makes up for it by, well, being really big.
Source: Game Informer