Sadly, the context is literally just a list of magic items you find in the treasure vault...
Okay, here is the full List:
12th level Spell-Storing Ring
x4 Staff of Firebolts
X4 Staff of Windrunning (?)
+4 Staff of Dark Summons
20th level Ring of Demon Mastery
20th level Book fo Path Mastery
Boots of Invisibility
Mace Gauntlets
Pouch of Water summoning (this one and the gauntlets they explain how they work).
Yeah, I kinda thought the 4X staff might be 4 x a day...though of course it could mean 4x damage (though that seems superinsane).