For those unfamiliar with the archetype, what the idea is to play cards that generate four mana, with at least one black mana, then cast either Balustrade Spy or Undercity Informer. Because this deck has no lands in it (hence the name), the ability of either rogue, once used, dumps the entire library into the graveyard. All copies of Narcomoeba in the library can be placed on the battlefield, then sacrificed to flashback Dread Return. With Dread Return targeting Angel of Glory's Rise (this has been replaced with Underworld Cerberus in my current build, as indicated in the update), all humans in the graveyard go to the battlefield, including Laboratory Maniac and Azami, Lady of Scrolls. Azami's ability is used to draw a card, which triggers Laboratory Maniac's ability for the win. What makes this viable is sheer speed. From what little goldfishing I've done, this is one of the fastest Legacy decks I've ever tested.
This is only the initial version of my decklist, constructed from my incomplete understanding of the archetype. If I get enough testing in, I'll make some (relatively minor) modifications.
I have replaced Angel of Glory's Rise and Azami, Lady of Scrolls with Underworld Cerberus and Bridge from Below. Bridge from Below was advocated in early versions of this deck, back when Gatecrash was new, the idea being that, by replacing sacrificed Narcomoebas, it could allow for an extra Cabal Therapy even when a Narcomoeba and a creature necessary for the finishing combo are both drawn.
Underworld Cerberus is an alternative Dread Return target. While I have yet to see someone else use it, I have seen it mentioned. With Dread Return on Underworld Cerberus, victory is achieved by exiling three of the "Spirit Guide" creatures, playing Wild Cantor and sacrificing it for a blue mana, hardcasting Laboratory Maniac, and cycling a Street Wraith to trigger Laboratory Maniac. The advantage to this version is that Underworld Cerberus only takes one slot and replaces both Angel of Glory's Rise and Azami, Lady of Scrolls (which not only makes room for Bridge from Below, but also reduces the chances of drawing a creature that I'll need to Cabal Therapy out of my own hand). The disadvantage is that cycling a Street Wraith costs 2 life. The advantage should easily outweigh the disadvantage in this case.