I have built this commander deck to be a competitive deck to take to GPs if I don't succeed in the main event or I don't want to take part in it. The deck is entirely built to be a Laboratory Maniac deck, and while cards like Jace, the Mind Sculptor and Keranos, God of Storms can act as a way to win the game, they are absolutely secondary win conditions. The deck is entirely dedicated to assembling the combo, whilst protecting itself and trying to disrupt anything the opponents doing if necessary.
The Main Combo:
The deck has 2 main ways to effectively remove the majority of the cards in you library, being Doomsday (where you would set up the library to win the game) and Demonic Consultation otTainted Pact (by naming a card that does not exist in the library, or thanks to having snow-covered basics, no two cards share a name). Do so with caution, because both of these are very "all in" because if you cannot resolve your Laboratory Maniac you WILL kill yourself. I prefer to try and win with at least 2 means of protecting the combo.
Doomsday Piles:
The main power of Doomsday is that it is almost a one card combo, since it allows you to set up you library exactly how you would like it. There are two main variations of piles that can be used. Either are based upon the Legacy variants of this deck, DDFT and Meandeck Doomsday. These piles are purely advisory and practice with the deck will allow you to make similar piles which would work with different cards in hand and available mana.
DDFT:
Act on Impulse, Gitaxian Probe, Lion's Eye Diamond, Laboratory Maniac, Gush(another spell which actually draws cards would work alternatively - Gush is just a personal preference since it doesn't cost mana and is instant speed)
Providing I have the a way to draw into, and cast the Act on Impulse, and leave the pile the same, this will win the game the turn I resolve the Doomsday. By casting Act on Impulse I would exile the Gitaxian Probe, Lion's Eye Diamond and Laboratory Maniac, this means I can use the Lion's Eye Diamond to cast the Laboratory Maniac, I still have access to the Gitaxian Probe as a way to draw a card after I have discarded my had due to Lion's Eye Diamond's cost. I can then use the Gush to win the game in response to removal or if I am feeling urgent, I could cast it immediately.
Meandeck:
Mental Note/Thought Scour, Irrelevant Card, Laboratory Maniac, Unearth, Gitaxian Probe
The maths required for this pile are in general much simpler than for variations of the DDFT piles. As long as you can draw 2 cards, and have a spare Blue and Black mana, you can win the game. First, draw the Mental Note or Thought Scour and use this to mill yourself of the irrelevant card and Laboratory Maniac, it will also draw you into the Unearth which is used to return the Laboratory Maniac to the battlefield. Then using the second card draw effect, you draw the Gitaxian Probe, which will win you the game since it is the last card in you library.
If you have a Brainstorm in hand, or a Jace, the Mind Sculptor in play which has not been used this turn, you can put a counterspell where the irrelevant card would be, drawing that and the Mental Note or Thought Scour, and putting back a useless card and Laboratory Maniac. This allows you to gain protection for this pile by just resolving the Doomsday.
Because of the ability to insert protection and the easier maths, I generally prefer the Meandeck approach for trying to win, but it does typically require use of the graveyard, so it can be more easily interacted against.
Additional Combos:
If I have Kess, Dissident Mage in play, I can end of the previous players turn cast Intuition searching specifically for Unearth, Laboratory Maniac, and Demonic Consultation or Tainted Pact. This allows me to untap and win the game, since if they give me the Laboratory Maniac to hand (the correct move for the opponenets) I can cast it, then cast the Demonic Consultation or Tainted Pact from my grave, exile my library, then I just need to draw one card. Otherwise, I just need to cast the Unearth and Demonic Consultation from either hand and the graveyard, and again, just draw one card to win.
Individual Card Interactions:
Darkblast, if milled with a Mental Note or Thoughtscour can remove all 5 cards from your library post doomsday. Usefull if you either had Mental Note or Thought Scour in had and Laboratory Maniac in play, or if you had to use Sensei's Divining Top to draw into the pile with Laboratory Maniac already in play. Dakmoor Salvage functions similarly if you had to normally draw into the pile.
Predict can be used instead of Mental Note or Thought Scour, to get Laboratory Maniac into your graveyard. It is one more mana than the aforementioned cards, but is another way to set up counter magic into the pile.
Yawgmoth's Will can be used as a way to try and combo off a turn later if you anticipate more disruption than you can deal with, just make it you last card, and you could draw it naturally. Goes nicely with Lion's Eye Diamond to make it function like a Black Lotus.
We all know by now that Sensei's Divining Top is a busted card. With our full suite of fetch lands and tutor effects, we can look at a lot of cards to help assemble the combo. It is especially useful because it is a "free", instant speed, card draw effect we can use it to win the game with Laboratory Maniac out, and even though it may go on top of our empty library, we would win before that part matters. It also sets up out Miracle cards quite effectively.
Volrath's Stronghold can be another way we stop ourselves loosing if Laboratory Maniac keeps getting killed, since we can just make it the next card we draw again.
Chromatic Sphere's activated ability is a mana ability. Including the card draw. This means you have a way to win the game which CANNOT be responded to. It can also be activated in response to a Split Second spell, such as Sudden Shock.
