Rough sketch. Could use another win condition I suppose. The artifacts do some crazy stuff, though. If Ivory Tower isn't enough to hold off aggro, Propaganda combined with Storm Cauldron should do decently in a casual scene. I'd prefer the Ivory Towers, though.
This is my monoblack deck. The idea is to live long enough to get the Platinum Angel out. With correct play you should be able to remove most, if not all, of the opponent's creature removal, giving you an autowin with Platinum. Liliana is mostly for either tutoring Infest, Angel, or Sacrament. She is also for helping with the Mindsludge/Haunting Echoes combo. I'm still working on the sideboard.
I run mono b myself. I like your build but just out of curiosity :
1: Why are the Gatekeeper's sided?
2: Have you considered Consume Spirit?
3: How well does 3 mind sludge main decked work for you?
4: Have you also considered Nightmare?
I'm still undecided about the Gatekeepers. I think I need to up the creature control, maybe maindeck Infest or something. I have considered Consume Spirit, but find that it is too slow. I don't really care to do a whole lot of damage, just erase all of my opponent's answers for the Platinum Angel. The Mind Sludges are a large part of the machine. They are to (preferably) be immediately followed up by Haunting Echoes. I haven't considered Nightmare because I don't really care to do a whole lot of damage, just prevent my opponent from killing me before I put out the Angel, then prevent my opponent from killing the Angel. I do have an updated decklist, but I don't have time to post it right now. I will in a bit.
EDIT: So, after a bit of playtesting, I've developed the following list:
I think that maybe Pithing Needle might work better in the sideboard, but the sideboard is a work in progress. Out of two matches, best out of three, it's gone 2-0 both times. That's not a whole lot of playtesting, but I feel that I'm on to something here. Note that a key to winning is to remove their creature removal with Sadistic Sacrament and Haunting Echoes in order to flat out win with Platinum Angel.
Ya, I've been trying to brainstorm ideas to make it go faster, but it can go off 5th turn pretty consistently as it is. I would love to have some mana accel in it to get the Dream Halls out quicker, but I haven't found anything to help it as much as I'd like yet. High Tide seems like a gimme, but that would only speed it up one turn at best. Artifacts can't be ditched to play blue spells, so it'd be best if it were something blue. Until I find something, though, I'm going to have fun removing libraries from the game =D
EDIT: Been working on the list, and it seems to run more consistent with the following build. I've taken the Extracts out entirely, as they seem more of a "win more" card.
Unfortunately, trading scams like these are what make people quit Magic. This is why I will not trade with someone that I don't know to be trustworthy. I normally buy my cards from my local shop or I compare prices from trusted websites and buy from the cheapest.
It does suck, but the best methods that I've found are what I've written above. I would highly suggest letting everyone know about the people who enjoy ripping people off so as to prevent situations where new people get ripped off and decide to quit.
It's faster if you go U/G with Root Maze and Crop Rotation. If you draw a RM, Stasis and Forsaken City (or Crop Rotation) in an opening hand, and the opponent doesn't have a way to stop it quick, the game is over. Crop Rotation also helps with the Glacial Chasms. If you maindeck Howling Mines along with all of the above, then you just need Brainstorms and Impulses and you're set, the deck is fast and furious. I wouldn't go playing it in a Legacy tournament, but it wins a good amount, and it's relatively cheap to build.
4 Font of Mythos
4 Horn of Greed
4 Storm Cauldron
4 Teferi's Puzzle Box
4 Charcoal Diamond
4 Ivory Tower
4 Underworld Dreams
Rough sketch. Could use another win condition I suppose. The artifacts do some crazy stuff, though. If Ivory Tower isn't enough to hold off aggro, Propaganda combined with Storm Cauldron should do decently in a casual scene. I'd prefer the Ivory Towers, though.
4 Mind Rot
3 Mind Sludge
2 Haunting Echoes
4 Sign in Blood
3 Hypnotic Specter
1 Vampire Hexmage
4 Gatekeeper of Malakir
4 Vampire Nighthawk
3 Platinum Angel
25 Swamp
1 Haunting Echoes
3 Sadistic Sacrament
4 Infest
4 Archive Trap
3 Vampire Hexmage
4 Mind Rot
4 Sadistic Sacrament
4 Sign in Blood
4 Infest
2 Haunting Echoes
2 Diabolic Tutor
3 Mind Sludge
3 Liliana Vess
26 Swamp
This is my monoblack deck. The idea is to live long enough to get the Platinum Angel out. With correct play you should be able to remove most, if not all, of the opponent's creature removal, giving you an autowin with Platinum. Liliana is mostly for either tutoring Infest, Angel, or Sacrament. She is also for helping with the Mindsludge/Haunting Echoes combo. I'm still working on the sideboard.
I'm still undecided about the Gatekeepers. I think I need to up the creature control, maybe maindeck Infest or something. I have considered Consume Spirit, but find that it is too slow. I don't really care to do a whole lot of damage, just erase all of my opponent's answers for the Platinum Angel. The Mind Sludges are a large part of the machine. They are to (preferably) be immediately followed up by Haunting Echoes. I haven't considered Nightmare because I don't really care to do a whole lot of damage, just prevent my opponent from killing me before I put out the Angel, then prevent my opponent from killing the Angel. I do have an updated decklist, but I don't have time to post it right now. I will in a bit.
EDIT: So, after a bit of playtesting, I've developed the following list:
4 Mind Rot
4 Sadistic Sacrament
4 Sign in Blood
4 Infest
2 Haunting Echoes
2 Diabolic Tutor
3 Mind Sludge
3 Liliana Vess
26 Swamp
4 Crypt Ripper
4 Platinum Angel
Spells:
4 Duress
4 Mind Rot
4 Sign in Blood
4 Sadistic Sacrament
3 Mind Sludge
3 Haunting Echoes
4 Tendrils of Corruption
4 Gatekeeper of Malakir
4 Vampire Hexmage
4 Consume Spirit
3 Disfigure
I think that maybe Pithing Needle might work better in the sideboard, but the sideboard is a work in progress. Out of two matches, best out of three, it's gone 2-0 both times. That's not a whole lot of playtesting, but I feel that I'm on to something here. Note that a key to winning is to remove their creature removal with Sadistic Sacrament and Haunting Echoes in order to flat out win with Platinum Angel.
EDIT: Been working on the list, and it seems to run more consistent with the following build. I've taken the Extracts out entirely, as they seem more of a "win more" card.
26 Island
Enchantments:
4 Dream Halls
3 Eye of the Storm
3 Denying Wind
3 Time Warp
3 Time Stretch
4 Brainstorm
2 Reminisce
4 Impulse
4 Tidings
4 Opportunity
4 Brainstorm
2 Impulse
4 Opportunity
4 Denying Wind
4 Extract
4 Time Warp
4 Time Stretch
4 Eye of the Storm
2 Reminisce
Get Dream Halls, get Eye of the Storm out, remove their library from the game, make them draw cards.
It does suck, but the best methods that I've found are what I've written above. I would highly suggest letting everyone know about the people who enjoy ripping people off so as to prevent situations where new people get ripped off and decide to quit.