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.
