Grimmbone

This is basically the deck I've been dreaming of making, but there needs to be a better way to grab phenax. Personally I was thinking omen speakers would be a good way to dig and play nice with phenax thanks to their big butts.

Memory sluice isn't a bad option with the undead alchemist. You'll usually have enough zombies for it.
http://gatherer.wizards.com/Pages/Card/Details.aspx?multiverseid=158759

Have you thought about gyre sages? I know that it's not defender, but you can boost them with vorel, should evolve with the defenders and can be decent beaters.

For self mill, you could think about chronic flooding from RTR

Probably because you have both Obzedat, blood baron, and Frontline medic in your deck haha! Did you think about putting tithe drinker in there by chance? may be a better option than Sydic.

Toss in any black ninja with a cheap ninjutsu cost and you're set for a win con.

Nice, I like the idea of playing hidden strings with krenko

You ought to run orzhov charm for "return target creature card with converted mana cost 1 or less from your graveyard to the battlefield." works nice with the devil.

I've got a buddy who plays a similar double striking deck, though a little more streamlined.
He's rather fond of Ghor-Clan Rampager and bloodrushing onto his doublestrikers for +4/+4 and trample.
Also, wolfir silverheart is terrifying paired with a doublestriker.

Have you considered Treacherous Pit-Dweller? he's a good price for scavenge, and if you can get some counters on him he won't end up on someone elses team.

Glad to have been a help! Kick butt.

Now, if you want something that works kind of like the closet, may I suggest Teferi's Veil: http://forums.mtgsalvation.com/showthread.php?t=348362
It basically lets you keep your unearthed buddies forever since they don't technically leave the battlefield.

Reforge the soul is probably the best alternative...

Thanks. The Korozda guildmage is there mostly to net more blockers later in the game. Trading in a useless mana elf or a doomed traveler for a bunch of blockers is a pretty nice option, but I'll probably take another one out for exquisite blood.

Just out of curiosity, but have you thought of splashing black for vizkopa guildmage?
Her out, with a faithmender while playing a heroe's reunion can smack your opponent for 14 damage.

Have you considered playing with deathcult rogue instead of the Horror? While he's not going to be as big, more often then not, he'll probably be unblockable.

The idea of copying a guttersnipe with stolen identity makes me giddy! Love it.

I like it, but I'm not sure about the inclusion of the wight and the ruinator. Ruinator would work better with a self mill deck and the deck doesn't have any way to get bigger since the deck lacks milling, other than from the alchemist (who's gonna eat all the milled creatures anyway).

Update:
The combo, while fun, wasn't particularly competitive. Added in alt win conditions via the phantasm and guildmage. I also tossed in some more removal and duresses to nab planeswalkers and nasty enchantments. Still not sure what to put in the sideboard, so suggestions are welcome.

Thanks! I'm glad you like it. I'll probably add a couple of slimes. I might throw in one or two Gruul Ragebeasts for creature removal while I'm at it.

If you have any of the Gyre Sages, you should make sure they're in there. They're gonna evolve a lot.