doctorhydrogen

Vernal Bloom would be useful here.

Hall of Gemstone wouldn't affect you a bit, and would basically prevent anyone else from casting multi-colored spells.

I'd run Supreme Verdict over Damnation. Heck, I'd run Wrath of God over Damnation because if I had a deck that could use both it makes more sense to run the fifty cent card and trade the fifty dollar card for something else useful that doesn't have a fifty cent replacement :)

Just pointing it out because you missed non-basics like Stomping Grounds with are fetchable with most land fetches and also provide red, etc.

Or you an be defensive. That's cool, too.

manabasecrafter.com is a fantastic site for finding what lands you can run. I think you can run a few less mountains, but you don't want to skew it too much. 12 forests to 8 mountains wouldn't be unreasonable.

As for cuts I think Bow of Nylea, while a cool card, doesn't add much here. Deep Recon seems a bit weak compared to your other land ramp spells, too.

Ugin is a good fit into any deck . . . which is what makes him a pretty boring inclusion.

Harmonize is good, Soul's Majesty is solid, Greater Good is really solid and it gives you a way to mass destroy elementals to for a death blow on someone, and Collective Unconscious might be worth it if you find yourself making a lot of tokens.

Grazing Gladeheart seems weak, and you can probably pull most of the "tap to play an extra land dudes" since you have almost no draw so you're not going to have many extra lands to play.

I'm converting my Damia landfall to Omnath and it's here if you're curious: http://www.mtgvault.com/doctorhydrogen/decks/omnath-locus-of-rage-edh-2/

New Omnath:

Omnath, Locus of Rage 3RRGG - Mythic Rare
5/5

Landfall - Whenever a land enters the battlefield under your control, put a 5/5 red and green Elemental creature token onto the battlefield.

Whenever Omnath, Locus of Rage or another Elemental you control dies, Omnath deals 3 damage to target creature or player.

Gruul Warchant accomplishes the same thing as Caterwalling Boggard but is harder to remove

Long-Term Plans is a nice way to get that Blightsteel or whatever into play.

30 lands seems really, really light. I wouldn't be comfortable under 34, and even that seems tight.

Tolarian Academy is banned, which is why it's not a $150 dollar card like Gaea's Cradle :)

For one more mana than Brilliant Plan you can probably draw 3x as many cards with Recurring Insight in most games.

You have two copies of Demonic Tutor.

Survival Cache seems safe to remove.

Alhammaret's Archive is brilliant in Oloro.

I think Angelic Accord would make you a lot of angels.

Farhaven Elf gets any basic so that might fit your needs better than Wood Elves. Bear in mind though that Wood Elves and Seedguide Ash fetch forests with no stipulation they be basic forests so that means you can get Overgrown Tomb with it which you're already running, or Temple Garden or Murmuring Bosk if you ever choose to add those.

I'd also consider Utter End somewhere as a removal spell. Yeah, it's one more mana than Putrefy/Mortify, but it's an exile effect and it hits any non-land target. IMO it's worth spending one more to be able to hit anything.

I think you need more ramp if you're playing to win. Sol Ring and Orzhov Signet would be decent starts, and I'd strongly consider Thran Dynamo, Gilded Lotus, Worn Powerstone and Mana Vault. Mana Crypt is great too, especially in a lifegain deck but it's like a $180 dollar card or something. Sitting doing nothing for 5-6 turns loses games so you want to get to your stuff fast.

A Demonic Tutor is worth the $15 dollars if you can find one over Diabolic. Those two mana are often times the difference between casting what you just tutored for this turn, and waiting.

Cabal Coffers is a monster in most two color decks with black. You can also run Expedition Map to fetch it.

Wrath of God is strictly better than Day of Judgement. I'm a huge fan of Austere Command though, and also Merciless Eviction. The flexibility on both is amazing.

I like Banishing Light and Oblivion Ring over stuff like Arrest and Pacifism because they can hit any target. They don't work quite as well on commanders as does the other two because someone can just recast their commander out of Oblivion Ring, but more often than not the flexibility is well worth it.

Things I'd remove:

Deathrender: Nice, fun card, but it doesn't win games.

Chanellor of the Dross: Fine card, but for that many mana it needs to impact the game immediately.

Serra Avatar: Same as Chancellor of the Dross. If I wanted to spend that much white mana I'd run Avacyn. She breaks everone's heart when she lands. Serra Avatar gets chump blocked five turns in a row without a trample enabler.

Replace Naturalize with Deglamer or Unravel the Aether. Nothing sucks more than holding a Naturalize in hand while starting at a Xenagos giving stuff double strike or a Purphoros in a token deck or a Blightsteel Colossus and being unable to do anything about it. Plus stuff is harder to get back from a tuck than it is the graveyard, and it avoids triggers like Wurmcoil Engine, etc.

I'd replace Explosive Vegetation with something like Wood Elves or Seed-Guide Ash. Why not make your ramp be something you can recur with Karador?

I was kinda messing with an Oloro deck that I never made using extort: http://www.mtgvault.com/doctorhydrogen/decks/oloro-ageless-ascetic-edh-2/

There's probably a decent deck to be built combining that with all the life-gain alt win conditions

This is probably not what you wanted to hear, but as the deck stands now you could probably substitute Oloro (he's slouching in a throne, too) as your commander, never cast him, and still have him contribute more to your win con than Vish Kal just by chilling in the command zone gaining you life. Vish is kinda cool, but he's really build-around, and you're not building around him at all.

That isn't to say the deck won't work, but as it stands now you're taking the path of most resistance :)

Probably Charnelhoard Wurm. That casting cost is brutal for a 6/6 with trample that might get you a card back.

Druids' Repository generates stupid amounts of mana in Prossh, and it's a cheap card.

manabasecrafter.com is a fantastic site to see what lands/rocks work in your particular color scheme.

I'm not a fan of Vivid lands. They enter tapped, and stop being duals after a few uses. I'd much rather run something like Darkwater Catacombs or Tainted Isle in those slots.

Tolaria West lets you tutor up Cabal Coffers with sucking up a deck slot.

If you're looking for a slot for Black Sun's Zenith, pull Unholy Strength. It's not going to win games, and it's just asking to get two-for-one'ed when someone kills the creature.