If you know that goblins (or thresh for that matter) are really big in your area, then you should probably gloss over the Nether Spirit/Chimeric Idol route.

There are much better creatures for dealing with aggro that Pox can use. Plague Spitter and Necroplasm absolutely wreck these decks. Necroplasm is essentially a walking, living Powder Keg, and it's recurable. It's also a halfway decent clock (hit for 9 damage over 3 turns). Plague Spitter wreck goblins rather easily. It kills all the x/1's and forces Goblins to hold back and build up. This allows you to just can Pox and wrath them anyway.

On a side note about win conditions: I've found that most of my games were won by The Rack damage alone. A good mid-game Pox will end up dealing 4 damage on average once you factor in The Rack.

The strength of this deck is that Pox can be cast on either turn 1 or turn 2 and literally ruin your opponent's game. The loss of potentially 4 cards on the first turn is huge. (creature + land + 2 cards in hand) Pox is specifically designed to take advantage of the low resource game by attrition. This, of course, doesn't leave very many viable kill conditions. The artifacts are necessary to circumvent that. The Rack is passive and cheap mana cost, while Chimeric Idol is cheap to activate (and hits for roughly 1/4th the opponent's life total after a Pox). Both are usefull, but not necessarily together.

I think we can all agree that the basic shell of Pox should look like this:

17 Swamp
4 Wasteland
4 Dark Ritual
4 Duress
4 Hymn to Tourach
4 Sinkhole
4 Smallpox
3 Pox

Additions should really be based on your expected metagame. Against Aggro, more board control elements such as Powder Keg, Necroplasm, Plague Spitter, Smother, Innocent Blood, etc, are good choices. Against control, Funeral Charm, Phyrexian Negator/Totem, The Rack are great. There is not going to be a singular Pox deck that fits into every metagame, so don't look for one.