Mozex

Door of Destinies is useful in tribal decks.
I'd replace Urban Burgeoning with more counter-spells.

My suggestion is:
Less Chained to the Rocks, more Supreme Verdict and Detention Sphere.

You can do that with one Boros Reckoner dealing damage to itself. Boros Charm (WR) and Withstand Death (G) are the cheapest ways to get indestructible.

I suggest Goblin Arsonist over Rakdos Cackler.

I'd also probably take out Hammer for a fast-mana spell like Battle Hymn.

Voyaging Satyr is better (1 extra toughness) than Manaweft Sliver unless you add more slivers to the deck.

As he suggested, you could add the B/G and W/B fetchlands (Marsh Flats, Verdant Catacombs) to make better use of Deathrite shaman.

You've got a very reasonable mana curve. It seems like the usual 24 land would be sufficient.

"How to play" section is inaccurate. Since you're opening hand is seven cards you will lose before turn 50,000

Pyromaster's Gauntlet doesn't seem very good in this deck. You will cast pretty much all your burn spells before you ever play it. I'd run skullcrack instead.

Very cool deck.

What does the SGS tag mean?

Yep, that's the "almost as good" part. Don't you normally want to be burning life though? If that's your plan you could run both.

City of Brass is almost as good as Battlefield Forge for this deck.

20 lands seems very low

I'd use madcap skills in this deck

Druid's Deliverance might be a good fit for the sideboard against aggro or 1/2 copies in the main deck.

Wasteland Viper is just better than Sedge Scorpion.

Your turn 1 combo is only six cards so one Dark Ritual could be replaced by two Cabal Rituals (or two Simian Spirit Guides or two Elvish Spirit Guides). Threshold doesn't matter in this case.

Like I said it's only a slight increase.

Also running 4x Cabal Ritual would slightly increase the odds of getting this combo on the first turn.

I would go -1 dark favor / +1 Vampire's Bite. It enables you to infect on turn two more consistently.

T1: swamp Tormented Soul / Vector Asp
T2: land, Tainted Strike / Asp Activation + Vampire's Bite

... and they're at 4 or 5 poison