A few details of the Quest for Ghal Maraz have made it out now. A reader here on the site has chimed in on a few of the details that are found in the book, along with a little bit of the storyline.
Spoiler Warning.... Dont read below if you don't want to know.
via Norrikan in the comment section of Faeit 212
NorrikanAugust 12, 2015 at 12:27 PM
I have the new AoS book in hand now.
There are a handful of new warscrolls in there, discounting the stuff already shown the WDs. 2 new Stormcast battalions, 1 new Khorne battalion, 2 Nurgle and 2 Skaven ones.
Exalted Deathbringer has been leaked already, Bloodwarriors are the same, except dual axes trade in the Gorefist rule for rerolling ones to hit and every tenthBloodwarrior gets to replace all weapons with a Goreglaive, which is 1" A2 3+/3+ R-1 D2.
Lore is neat so far, but I've only managed to skim it. Sigmar get's back Ghal Maraz at the end, realizes that weapons are made to take into battle and then goes to open the Chamber Extremis to awaken the 'Holy Beast' within (which probably isn't Drakothion, who got hurt hurt badly earlier in the book fighting the corrupted wyrm Argentine). So, chances are Stormcast get either Sigmar mounted on whatever the 'holy beast' is or a independent monster.