parakkum and I hit the Shadowmoor Pre-Release yesterday, participating in both flights of individual sealed deck competition. With two booster packs and a sealed tournament pack the players are given time to make the best deck they can with the randomly cards they receive. Being able to do well in this format requires a degree of skill in recognizing how to compose a competitive deck, as well as a certain amount of luck.
For participating, we received a foil [Demigod of Revenge] with alternate art. The deck list as well as my matches are below in the extended.
So my roommate and i went to the LA prerelease. Playing in Wave E, we probably faced less impressive competition than the flights where you live. Still, we did all right, and spent a fair amount of the drive back up Sepulveda discussing the ins and outs of the format.
You definitely missed the boat on your Red burn spells in the first pool.
It seems like with the second deck, the GUw pool is the way to go. Spawnwrithe is not as bad as it looks at first blush-- we've all played Grey Ogres in Limited, and the ability is gravy, especially with the Giant Growth. Isleback Spawn is an out-and-out bomb, and you don't have a lot of mana search, but the Green build can stall for days.
Raking Canopy and Gloomwidow eat Silkbind Faeries for lunch. Even Cerulean Wisps are playable when backed by green fatties-- there are surprisingly few tricks that trump an untapping blocker.
Oona's Gatewarden
Medicine Runner
Pili Pala
Juvenile Gloomwidow
Gloomwidow
Scuttlemutt
Spawnwrithe
Thistledown Duo
Wildslayer Elves
Thistledown Liege
2 Safehold Duo
Barren Cragtreads
Glamer Spinners
Scuzzback Marauders
Old Ghastbark
Isleback Spawn
Safewright Quest
Barkshell Blessing
Manamorphose
Firespout (BOMB)
Cerulean Wisps
Curse of Chains
1 Plains
8 Forest
8 Island
Manabase might be all screwed up-- i didn't actually count mana symbols or consider early curve, though my gut says you may want go 9/7 in favor of Forests. I think the deck is also heavy a creature or due to cut the Safewright quest. The creature base here is all right, though you don't have a lot of persist-y bombs or ways to deal with counters.
Key sideboard cards
Put Away
Merrow Gloomblotter
Gloomwidow's Feast
Raking Canopy
Whimwader
In my experience, Traitor's Roar was not very good. I had it played targeting my 5/5 fattie, but it only works the turn he comes into play. (unless it has vigilance) Even with conspire, the second copy can't be used on the same creature.
For your first flight, you really should have gone Red/Green. Red removal, plus solid r/g and green creatures plus the bomb that is Howl of the Night Pack (especially since you have Elsewhere Flask).