Running 4 Spirit Guide instead of 3 Guide and 1 Desperate Ritual.  Ritual adds unnecessary inconsistencies to the deck by allowing our mana source to be countered.

On second thought, the Ritual allows us to play around Extraction effects a little bit, seeing as we wont have as limited of a supply of red mana.

Extra Pact in the board feels pointless with access to Silence.

Replaced Infest with Drown in Sorrow

Gifts combo in the board seems to be an okay out to Leyline.

Rain of Gore, Everlasting Torment, and Skullcrack/Flames of the Blood Hand are all possible options to deal with Soul Sisters

Cutting Favor of the Mighty due to the lack of Twin/Bogles

Replaced Conflagrate in the board with Lab Maniac.  Beats Leyline + Spellskite effectively. 

Favour of the Mighty is probably good again due to the popularity of Twin and Bogles, Night seems too expensive and whilst disrupting Twin completely, might not be what's needed to shut off Bogles in the early turn, and similarly Favour can be resolved in the early turns and shut off Twin pretty hard.  The only out to it is having Pestermite/Exarch + another creature with different power, i.e. Pestermite + Vendilion Clique, Exarch + Pestermite, etc.

Smother vs Another Wrath
Grave hate either Cage/Relic, Relic is probably better to draw

Alternate List?

Creature (4)
4 Simian Spirit Guide 
Sorcery (7)
4 Serum Visions 3 Sleight of Hand
Instant (16)
4 Ad Nauseam 4 Angel's Grace 1 Lightning Storm 2 Mystical Teachings 2 Pact of Negation 2 Peer Through Depths 1 Slaughter Pact 
Artifact (8)
4 Lotus Bloom 4 Pentad Prism
Enchantment (3)
3 Phyrexian Unlife 
Land (22)
1 Darkslick Shores 2 Flooded Strand 2 Gemstone Mine 1 Godless Shrine 1 Halimar Depths 1 Hallowed Fountain 1 Island 1 Marsh Flats 1 Plains 2 Polluted Delta 1 Seachrome Coast 1 Sunken Ruins 1 Swamp 1 Temple of Deceit 1 Temple of Enlightenment 1 Tolaria West 1 Urborg, Tomb of Yawgmoth 2 Watery Grave 60 Cards
Sideboard (15)
1 Pact of Negation 1 Phyrexian Unlife 1 Boseiju, Who Shelters All 1 Damnation 1 Drown in Sorrow 1 Echoing Truth 1 Favor of the Mighty 1 Laboratory Maniac 4 Leyline of Sanctity 1 Patrician's Scorn 1 Silence 1 Thoughtseize

-1 Peer Through Depths +1 Telling Time

Telling Time allows us to find Phyrexian Unlife as well as mana sources when they're needed.

+1 Porphyry Nodes -1 Drown in Sorrow