The Playhouse Cellar is a sub-location of the Playhouse on Lanilor Lane in Aleroth, and contains the quest objective Script for All the After World's a Stage. There is a locked entrance near Vito (next to Willy's House on Lanilor Lane), but it is perhaps more easily accessed from the backstage area of the Playhouse, through an unlocked trapdoor near Alfred.
Entering from the Playhouse, proceed north, where you'll battle some skeletons. Turn east, stopping partway along the hall to a recessed area in the north wall. Here you'll find a desk with a copy of the Chambers of Blood script (a quest item for All the After World's a Stage). On the wall just left of the desk, there is a button that opens a concealed area to the south.
Here you'll find a Charcoaled Manuscript (the Blutsporn edition of the script accidentally used by Tamara that summons the demon Astaroth). Behind the book is an unlocked chest containing the Order of the Viper Bracers, part of the Order of the Viper armor set.
Continue east, following the turns to the left (north), right (east), and right (south). Down the hallway you'll find an unlocked chest and a locked chest, both containing random loot. The ladder to Lanilor Lane is at the end of the hall.
- Ice Metal Skeleton Minions, Rangers, and Priests (level 37)
- Chambers of Blood Script (quest item)
- Charcoaled Manuscript (quest item, Blutsporn edition of the script)
- Order of the Viper Bracers
- Random loot in two chests
- Additional loot in some barrels, baskets, and crates