Locus Cube

Something like this, just to give you a few ideas.
http://www.mtgvault.com/ViewDeck.aspx?DeckID=128960

im sure there are many ways to beat this deck but its not really possible to make a deck airtight. That being said i understand what you mean, if the cards i have are there, this will work great but im relying to much on a multicard combo for this to work effectively.

hopefully now between the umbras and asceticisms, locus will be able to survive

I'm glad you fixed your mana accel, it's much more efficient now. I still think you need a secondary win condition, though. Something that doesn't rely on Omnath. Somebody suggested the legendary Eldrazi. This would be a good fix, especially if you included another Time of Need (or two). It's just, from my experience, decks with a single win condition are either hit or miss, and adding another creature into the fold that can end the game for you will create a more consistent deck.

Also, Mark of Sakiko is only effective if you can deal combat damage to an opponent. My suggestion is, instead of adding trample (a good idea, btw) is to run at least 2, preferably 3 Whispersilk Cloaks. These will proxy as Asceticism for a single creature, and make it unblockable.

After that, the deck is still subject to counters / control / the abundance of artifact & destruction spells. Your sideboard should be designed to protect yourself from this, otherwise your deck could fall apart at the seams. Avoid Fate is an amazing spell to begin with there :)

would a token generator and another big creature be a good option in the deck? i dont really like sideboards, i know they can be useful, its just a personal preference.

how is the deck now?

Just occurred to me that you're running all Elves for mana accel. As I mentioned with the legendary Eldrazi, you could include another legendary creature to make better use of Time of Need.. but I think Ezuri would be a better choice. IMO, that's where you should look instead of another big creature like Gaea's Revenge. You can funnel some of that abundant mana into Ezuri to give your Elves multiple Overruns and finish the game. Second win condition achieved :)

It is better now, though now that I've mentioned it I think Ezuri instead of Gaea's Revenge would seal the deal.

Oh, and if you want a token generator, look at Wolfbriar Elemental. I could see 4x of these finding a place in this deck too ;) Perhaps in place of Gaea's Revenge and 2 other cards.

Also, super tired atm, so I don't feel like reading up.. I don't remember if I suggested this or not.. But with 22 lands you could afford to exchange 4x of them for Oran-Rief, the Vastwood (even better with a Nature's Will in play) When you cast Wolfbriar, Oran-Rief will turn all of those 2/2's into 3/3's or bigger (up to 10/10's actually, if you have 4x Oran-Rief and Nature's Will in play)

the one that gives me mana for damageis awesome, if his damage is my mana, then in effect it would be doubling my mana.. if all the damage is dealt of course. if not im still getting a more powerful creature. And the untaping of land is again going to allow me to tap it all again and make him more powerful for the next turn.

You are right about lands untapping and I didn't think about that but getting more random mana with nothing to put it into isnt going to help. it gives you mana after the damage step therefore the powerup to omnath is somewhat worthless. He's just going to lose it at the end of the turn. Istill suggest putting in soumething that costs a god awful amount of mana that you want to play such as Emrakul or something with X in the mana cost so X can be gifreakingantic. and you'll have the lands untapped just in case someone feels like bolting omnath

that mana doesnt leave after the turn is over.

ok i feel dumb. i didnt think that the mana chilled over turns. my bad.

man.. i really like a few of those but i dont want to stray from my original goal, id like a token generator too, just for chump blocking, but yeah. You know what i mean.