This is my version of Mono Green Tron without using the Tron lands. I don't like to use the Tron lands because it makes me feel cheap, so here is my compromise.
In my experiences, this deck is unique. I have not seen another Mono Green Spawnsire of Ulamog deck that functions the way this deck does. I have only seen infinite combos using Spawnsire of Ulamog and cards like Training Grounds paired with the tron lands as apposed to using Vernal Bloom and Primeval Titan.
The fastest ive ever hit Spawnsire of Ulamog's ultimate is turn 5.
Here's How:
Turn 1: Land, Arbor Elf
Turn 2: Land, Utopia Sprawl on untapped land, tap/untap/tap land to get 4 mana, Vernal Bloom
Turn 3: Land, you now have access to 10 mana (the land with Utopia Sprawl on it taps for 6 w/ Arbor Elf, the other two lands tap for 2 each) and 3 cards in hand assuming you went first. From here, there are a couple ways to get to 30 mana:
Primeval Titan --> Arbor Elf or Vernal Bloom or Utopia Sprawl or a land (next turn) + an Early Harvest next turn
Arbor Elf --> Utopia Sprawl + Early Harvest
Turn 4: Draw a card (it'd have to be a Spawnsire or an Early Harvest if u had Spawnsire in hand) and then Spawnsire ftw!
Props and all credit to hungry000. After the deck update, he was the one who crunched the numbers and figured this out. It is a turn 4 Spawnsire of Ulamog activation now! Thank you hungry000.
So, here is my deck!
Mono green mana ramp centered around getting Spawnsire of Ulamog ultimate ability out around turn 8 at the latest. Any later and you've already lost.
Endless One gives me a second win condition paired with the mana ramp so it can be played fairly large quickly and easy.
My mana starters are Arbor Elf and Utopia Sprawl. Duh. No explanation needed there.
Omnarth, Locus of Mana alows you to store mana, which can quickly pile up into a Spawnsire same turn Ult, or a 30/30 Endless One.
Primeval Titan paired with a combination of Arbor Elf, Early Harvest, or Vernal Bloom can make insane amounts of mana, especially when you have several of these components and the mana to use them. Depending on the board state, Primeval Titan can win you the game, being a beefy 6/6 trampler that gets more mana every turn.
From Beyond lets you search for your main 2 win conditions those being Spawnsire of Ulamog and Endless One. It also creates even more mana making in the form of Eldrazi Scions.
I love Vernal Bloom in this deck because it basically says "All lands tap for (2 green mana). This couple really well with Early Harvest, being able to tap all my lands, using 3 Green for Early Harvest then tap all my lands a second time for a nuts amount of Green mana.
Heroic Intervention is the to protect against the odd kill spell whether it against Omnath, or Spawnsire or Endless One.
Harmonize provides some card draw so you can find the forests and win cons that are so important.
Sideboard
I stacked my Sideboard with some of the most overpowered eldrazi legal in modern. Unfortunately, this also means you have no Sideboard while playing this deck.
You could probably cut it down to just the three Titans and still have a Sideboard of 12.
I included a playset of Desolation Twin because 8 10/10s is just too overpowering and gives a target for an early counterspell or kill spell in case they are saving some. I also play a playset of Ulamog, the Infinite Gyre because you cast you're Eldrazi not dump them all at once, so not only do I get to keep an Ulamog on the board I get to destroy 4 target permenants and shuffle the 3 of Ulamogs into my library, along with my graveyard.
Strengths
This deck preform well against slower decks, or decks with little disruption. Turbo Fog, Scapeshift decks, Tron ect. Basically anything that can't or won't interfere with you board state.
Weaknesses
This deck preforms poorly against faster decks with a fair amount of disruption. Jund, Control, Midrange, Aggro etc. It seem to preform particularly poorly against Jund and Control/Midrange, as you have no way of stopping them from removing all of you stuff.
I've gotten mixed results playing this deck against combo decks: KCI, Storm etc. Sometimes it is faster than they are and can hit the wincon before they can pull off their combo, but it has no way of stopping them, letting them put together the combo with no disruption.
I have consistently gotten a turn 6-7 activation of Spawnsire of Ulamog's ultimate ability.
My Maybeboard is for others who might want to tweak the deck. I will continue to add more to it, the more cards I find that COULD fit the deck. I HEAVILY encourage others to make their version of this deck. Share them with me either at my profile page here: Catpocolypse, or here in a comment. I want to see how others build around Spawnsire of Ulamog which in my opinion, is a very under utilized card.
If you liked my deck and want to see my jankass snowballing, give a comment or a like and and don't be afraid to give me some suggestions. If you want to see more of my decks and the jank that is my way of logic, check out more of my decks at my page here:Catpocolypse and give those decks a like if you enjoyed them too.