Here is my take on the deck:
Creatures 194
Abyssal Persecutor4
Dark Confidant4
Plague Spitter4
Vampire Nighthawk3
Stoneforge MysticSpells 164
Swords to Plowshares2
Innocent Blood2
Hymn to Tourach4
Thoughseize4
Cabal TherapyArtifacts 41
Umezawa's Jitte1
Sword of Light and Shadow1
Sword of Fire and Ice1
Basilisk CollarLands 214
Scrubland8
Swamp1
Plains3
Wasteland4
Marsh Flats1
Polluted Delta
The biggest change is my swapping out Gatekeeper for Plague Spitter. I remember this buy being great against merfolk back in Masques/Invasion Standard. In this deck, he still does that quite well with a few extra added friends to be more powerful! The best way to utilise him is putting a Basilisk Collar on him, making him a board Sweeper, whilst gaining you a bunch of life. If you cannot wait for your next upkeep, just equip and then sacrifice him to Therapy or Innocent Blood. This little trick will kill nearly everything on the board, including all merfolk, Emrakul, Goyf, goblins, etc. Unfortunately, it doesn't kill Pro, but if that's the case, we have innocent blood and SBed Gatekeepers for that.
It's my little take of it. I haven't done too much testing, but I do like Spitter in place of Gatekeeper. Both kill creatures, both effectively costs 3 (spitter only takes one black, making mana better), both swing for 2, but spitter has the potential to kill more creatures and can deal more damage to your opponent.