I can't possibly believe that you can support a deck with 4 Smallpox, 4 Poxes and 2 Deathclouds off of just 22 land!!!

25 is the minimum unless you're playing Flagstones IMO and that's without the death clouds.

I would cut Death Cloud and Engineered Plague for Rancid Earth or Thoughtseize or something.

Otherwise, the build looks cool.

Sample Contamination Deck

Utility
4 Sensei's Divining Top
4 Beseech the Queen

Threats
4 Bitterblossom
3 Nether Spirit

Disruption
4 Thoughtseize
4 Cabal Therapy
4 Duress
4 Hymn to Tourach
4 Contamination
4 Damnation

Mana
4 Dark Ritual
4 Wasteland
3 Sheltered Valley
2 Mishra's Factory
2 Urborg, Tomb of Yawgmoth
3 Polluted Delta
3 Flooded Strand
5 Swamp

IMO, Contamination doest work very well, and is an autoloss against Black decks.