doctorhydrogen

Good call on Malignus. I was running Grove Rumbler in that slot because he has trample baked in, but I'm running Warstorm Surge and Where Ancients tread, so Malingus is a flat-out kill spell for one more mana.

I also like Fertilid there. I had forgotten he's an elemental, so why not have your ramp also be a guy that deals damage when he dies? I'll slot him in over Solemn Simulacrum. I hate running Solemn anyway because he's such a boring-ass generic staple that every crappy netdeck every build slots in just automatically.

I need to find a slot for Soul of the Harvest, too. I cut it really quickly from my deck before playtesting, but seeing it here in yours I think I want it back to try.

I've been playtesting my version of this deck for a week or so with proxies against friends. Some observations:

Wilderness Elemental is almost always bigger than Molimo, and is a lot easier to cast. Not that Molimo is bad, but this deck is mana hungry and has a high CMC, so that was a move that I was happy to make to lower costs a bit.

Mana Echoes generats DUMB amounts of mana here.

IMO Elemental Bond is going to draw you more cars than Font of Mythos, and it won't help anyone else in the process.

Eternity Vessel was a waste of slot for me. I just didn't need the life reset any of the five times I had it out in testing.

Blighted Woodland has been great. I doesn't come in tapped so there isn't really a tempo hit nor any rush to use it, and people tend to forget it is there until BOOM two extra landfall triggers.

I found I liked Goblin Bombardment as a sacc outlet more than Altar of Demetia. There's just too many decks that actually want stuff in the yard, and even decks that don't have graveyard themes sometimes have flashbacks as I discovered accidentally milling a Army of the Damned against a token deck :/ Plus dealing damage off the sacc is always useful.

NP, have fun with it.

Oh, and if you do put in Unshackled, find a slot for Fertilid. It's a decent way to ramp, but you can TARGET who searches for the ramp, and there is literally no better way to win a game than forcing someone to tutor for 2-3 lands with Ob NIx on board, making them taking 30 damage and sacc three creatures.

Ob Nixilis Unshackled is a great card in +1/+1 counters deck (I run a Mimeoplasm +1/+1 deck).

If you can find one Vigor is AMAZING.

Cauldron of Souls does really great work. Often times when stuff comes back it comes back with +1/+1 counters to eat the -1/-1 from persist letting you use Cauldron on the creatures again next turn if need be.

I found Inspiring Call usually drew me at least as many cards as Harmonize, and often times more, plus it had the flexibility of protecting against a board wipe if need be.

Consider Overwhelming Stampede. With some huge Realm Seekers or something on board you can use it to kill 5 people at once giving all your dudes +20/+20 or whatever.

Hatred makes a good win-con in Oloro.

Since you have Cabal Coffers and Dark Depths why not run Vesuva to copy either, or Tolaria West to tutor up either. I see Vesuva is in your sideboard, but it's probably worth finding room.

In my experience Recurring Insight almost always draws more cards than Opportunity for the same mana, and pretty often it draws twice or three times as many cards.

I'll keep any suggestions to sub-dollar cards:

Deck needs more draw or you'll be in top-deck mode by turn four. Soul's Majesty, Hunter's Prowess and Hunter's Insight are all fantastic in Dromoka since they can't be countered or the creature removed when cast during your turn. I'd find room for all three.

I'd get some more ramp in there. You've got a ton of dudes and I would imagine you want to cast them asap. Nature's Lore, Cultivate, Explosive Vegetatiopn, Kodama's Reach, Rampant Growth, Skyshroud Claim, Selesnya Signet and Talisman of Unity are all nice ramp cards and all should be like a quarter.

I'd find room for some more removal. Fate Forgotten is good which you have, but you could easily slot in Unravel the Aether, Swords to Plowshares, Banishing Light and Return to Dust.

IMO most decks need at least a board wipe or two for when someone else gets way ahead. Day of Judgement is dirt cheap, and the instant speed option on Rout or Fated Retribution is nice.

Drana's Emissary from Battle From Zendikar would be a nice addition as would the new black/white land.

I ran Sydri for awhile, first as a creatureless deck with a ton of tax/Pendrell effects, and then in a build similar to this. I always felt like I was just running not-as-good Muzzio or Arcum deck. That said, Arcum as a commander is super cheeseball, so at least Sydri is interesting :)

I'd find for Muzzio, he's really strong.

Since budge doesn't seem to be a huge issue why not just run Demonic Tutor over Fabricate? It's cheaper AND can hit any spell if you're desperate and need a Cyclonic Rift or whatever. Even Diabolic Tutor is probably better, one mana to get anything and not have to reveal it seems worth it more often than not.

Proteus Staff did good work for me. Being able to turn that Mana Vault late game into a dude is really useful.

I think it's probably better for multi than 1v1, but it should be competitive either way.

Evolutionary Leap has been amazing in my Karador deck.

With that many dudes Lurking Predators would probably do good work.

Wall of Reverence is a good card but probably expendable, and order of succession seems really risky and is basically destroyed by a Homeward Path.

Good luck against your brother!

I'm running mono-black vampires (http://www.mtgvault.com/doctorhydrogen/decks/drana-bloodchief-edh-3/) and here's a few observations:

Mana doublers flat out win games for me. You've got Caged Sun and Nirkana Revenant, but Extraplanar Lens and Gauntlet of Power do great work, and I even run Doubling Cube.

Expedition Map is a great way to find Cabal Coffers, and Wayfarer's Bauble is one of the few ways to ramp swamps.

The elementals with the hybrid casting cost wouldn't be legal in an Ashling deck.

Oh, and respect for not running Felidar Soverign or Sanguine Bond :)

Chromatic Lantern has the same cmc as Obelisk of Esper, taps for the same mana, AND fixes all your lands. There's no reason not to run it over Obelisk unless you're trying to save three dollars :) At the very least swap it for Darksteel Ingot as that also costs three, makes the same mana, and is indestructible as a bonus.

Terminus is a really good card, but you aren't running Divining Top or anything to fix your draw so it's a lot harder to hit miracle, especially in a draw-heavy deck like Oloro. Since the odds aren't great you are going to hit miracle, I'd run Merciless Eviction for the same CMC. Exile is more or less going to function the same as tuck now that you can't bury commanders, which means that in exchange for giving up a fairly small chance to hit miracle you also get the option to hit planeswalkers, artifacts or enchantments. That seems to be a worthy trade-off.

Dissipate is probably slightly better than Undermine. I'd trade exiling the spell over a shock. But I hate seeing people recur stuff from their graveyard. No means no!

Utter End does cost one more than Mortify, but it hits any non-land target, and it's an exile spell for those pesky Blightsteel Colossus or Darksteel whatever or Avacyn, etc.

It's not a game breaker or anything but Tolaria West would be useful here. Being able to tutor up Cabal Coffers or Urborg if you have Coffers already or even Reliquary Tower if you have a fistfull of cards can be invaluable, and it doesn't suck up a card slot other than displacing an island.

I do still think Nykthos would be fantastic here. You can afford to tap for colorless until you've got solid devotion in a two-color deck. I run a lot more utility lands in my azorius build with no problem, and it's probably more mana intensive than your deck: http://www.mtgvault.com/doctorhydrogen/decks/isperia-supreme-judge-edh-4/

I guess it depends on the meta, but with no evasion I can't imagine you'll successfully deal damage with Cephalid Constable very often. Sure, there's going to be weird situations where it works, but Michiko Konda works every time. She never doesn't have an impact people's choices where as Constable gets chumped 99% of the time and dies.

Mutation maybe Condemn? It's a good, cheap card, but it's a lot weaker with tuck gone, and it doesn't do any good when there's an Elesh Norn or Sheoldred sitting there being a dick but not attacking. That's a tougher call though as Condemn is still pretty solid.

I'd get a few more pieces of equipment with hexproof/shroud, because I can think of very few tables where GAIV wouldn't be target number 1 the second he hit the board.

Michiko Konda, Truth Seeker would be a good fit here imo.

Nykthos would probably generate you really solid mana with that many enchantments.

Don't underestimate Darksteel Mutation as a control tool. Being able to lock down a commander and make it useless so it can't be recast is really effective.

For something interesting you could run this artifact-free and get your ramp from Wild Growth-type enchantments, which also procc draws off Eidolon and the Enchantresses while giving extra punch to Ancestral Mask and Ethereal Armor. You can then run mass artifact hate if like Titania's Song or Creeping Corrosion.

In a deck with this many big beaters Greater Good is excellent, too, even if you just use it as a response to removal or board wipes.