You should really add Helix Pinnacle and Dawn's Reflection if you don't already have them. Otherwise, the deck is pretty good. :)

Gauntlet of Power

Also, Sylvan Primordial is banned

I thought about adding in Gauntlet of Power but I would have to get one, and I didn't know Sylvan Primordial was banned did that happen recently.

Yeah, I gather that's a recent development since a lot of people still have it in their decks.

What if I steal your Sword of Feast and Famine ? I know it is a good card for this deck, but it also grant protection from green. Do you have something to handle it if someone take control of it?

Also, I forgot to talk about Sakiko, Mother of Summer . I know you have Mark of Sakiko , but it would be great for all your creatures to do the same thing, the ramp would be faster. You can also add Swiftfoot Boots , even if it is similar to Lightning Greaves , because it is extre protection for your Omnath, Locus of Mana . A Fireshrieker would also be good for double strike, so Omnath, Locus of Mana would grow faster.

Depending on what the board looks like hopefully my eldrazi will force my opponent to sac the sword to annihilator, if i hard cast Ulamog, the Infinite Gyre i can destroy it or if It That Betrays is also out i might be able to get it back. If my opponent were to use the sword to chump block thats what trample and Blightsteel Colossus are for. Alternatively i could pump Omnath and unattach Surestrike Trident for a good bit of damage and bypass the sword altogether.

Ok, you are well prepared for it, but what about the suggestions I wrote just after?

I could switch out Mark of Sakiko for Sakiko, Mother of Summer it would be nice for all my creatures to have that ability, and between Fireshrieker and Doubling Cube Omnath could get crazy big in just one turn. I think i have a pair of Swiftfoot Boots somewhere that i could try out as well

I get a lot of use out of Rogue's Passage in my omnath edh.

ill have to test Rogue's Passage out i'm sure it will come in handy, i was just trying to keep colorless mana to a minimum

I don't think Patron of the Orochi + Umbral Mantle does what you think it does, it doesn't go infinite because you can only activate it's ability once per turn.

Slight oversight on my part but once a turn is still good

it's still good though. keep in mind, synergies and combos don't have to be infinite

why not Karametra's Acolyte ?

Karametra's Acolyte would be something I wouldn't mind testing out, just wish it was and elf and not a human.

Engulfing Slagwurm +Lure ?

i forgot to list an infi mana combo, Karametra's Acolyte + Primalcrux + Staff of Domination or Umbral Mantle for untaping the acolyte

Ulvenwald Tracker is good for removing creatures if needed but if you have Vigor out you could have your boss fight your own creatures to give them an insane number of counters after blockers are declared.

Ulvenwald Tracker is really nice I could see that getting out of hand fast with a few of the creatures in this deck

Solid deck. +1. I love mana manipulation.

You might benefit from an Akroma's Memorial . Also, it was mentioned by ComboMasterPro already, but Helix Pinnacle would be a cheeky addition to your deck.

FYI with the new Commander ban list update, Rofellos, Llanowar Emissary is completely banned in the format.

Nim Deathmantle doesn't work so well in green EDH... ruling says they the equipped creature becomes black (and loose all other colors) which means that your green mana becomes colorless, and Omnath, Locus of Mana is still effectively useless, unless you have a way to un-equip him at instant speed. Don't get me wrong, I love he idea (I even had it in mine for a time, until someone pointed me to the ruling)

Also, I'd suggest Nissa, Worldwaker to replace Rofellos, Llanowar Emissary

I don't see why Nim Deathmantle would effect Omnath, Locus of Mana . Am I missing something? What does the fact that Nim Deathmantle makes a creature black change about equipping it to Omnath, Locus of Mana ? Why would the mana become colorless, especially since Omnath, Locus of Mana doesn't actually have anything to do with producing the mana.