The Silmarillion

Silmarillion, The, n., p.n. 1.J.R.R. Tolkien's prequel to The Lord of the Rings, published posthumously in 1977. 2. (gamerese) any unnecessarily long or pointless exposition.
Ex: GM: "You're standing in a grassy meadow, surrounded by a stand of rowan trees. The meadow is atop a massive tel, in which is said to be buried Aygran Longlance, first King of the Sylvan Elves. Looking south, you see --" Player: "Aw, skip the Silmarillion, who do we kill?" [GJ1]