After testing a bunch of Crown/Roaches builds, this is the list I have arrived at. Credit to Camomilk for the Whispering Wind idea.
What the deck attempts to do:
Play a Crown of Possibilities, play Clockroaches, overwhelm the opponent. Once the engine gets rolling, 10/10 Clockroaches with every ability under the sun will make short work of the opponent. Echo and the ability to rebuy Clockroaches with Dark Return, Twinning Ritual and Second Sight create card advantage even in the face of sweepers.
How it gets there:
This list is focused on executing the main game plan. If you fail to draw your Clockroach and/or Crown, Whispering Wind is there to help you out. Most cards cost two power and Whispering Wind will allow you to discard them to get either a Crown, a Roach or an Avisaur (more on that later). Blistering Wasp, Permafrost, Annihilate and Lightning Storm serve to slow down aggro decks.
Cards we're not running:
Piercing Grief: I have seen this card in some lists and I can't fathom why. It doesn't do anything other than gain three life.
Initiate of the Sands: The deck has almost no cards that cost more than three power, so the acceleration from initiate isn't all that relevant.
Excavate: With four Dark Return, Excavate isn't needed. Also, it costs one rather than the two we want for Whispering Wind.
On the chopping block:
Tock Tick: It has good synergy with the deck and serves as an early blocker if need be, but it's overall pretty weak.
Nesting Avisaur: Great synergy with the deck and a fine card, but it costing four can make it awkward when you draw it off Whispering Wind.