More or less what it says on the tin. I've got an Artificer at level 6 and two ranks, and a little spare cash to toss around.
I already have the Korthos, Waterworks, and Catacombs pieces. Catacombs is also the only pack I have. I plan on picking up all (or most, at least) of the packs eventually.
Are there any other rune arms that would be worth buying a pack primarily for (with exp, favor, and other loot secondary/tertiary considerations)?