This is a version of the infinite turns combo using Sage of Hours + Sandsteppe Mastodon + Temur Sabertooth
. Big elements of the deck outside the combo are the Hornet Queen and Hydra Broodmaster. These cards are amazing in this deck with all the mana you can generate with your acolytes and Nykthos, Shrine to Nyxs.
So how it works is like this. You have the following cards in play, Temur Sabertooth and Sage of Hours, and enough mana available to cast the Sandsteppe Mastodon along with activating the sabertooth's ability. You then cast the Sandsteppe Mastodon. It's bolster trigger happens and you put all 5 counters on the Sage of Hours because it has the least toughness of creatures you have in play. You then activate the Sage of Hours's ability, remove all 5 counters and take an extra turn after this one. Then, because you have the ability on the Temur Sabertooth to return the Sandsteppe Mastodon to your hand in the same turn you cast it in you can just keep repeating this combo over and over again for infinite turns.
With infinite turns, you should be able to find a way to finish off your opponent. Here is the card breakdown:
The Creatures:
Hornet Queen: Obviously she is in the deck as both defense and offense. Generating a swarm of deathtouching flying little monsters is usually a good way to win games. Because of the Temur Sabertooth you can keep returning her to your hand and casting her again to create a veritable storm of stinging death dealers.
Hydra Broodmaster: This card is in the deck as an alternative to the Hornet Queen in case she gets hated out or a way to go large with creatures if needed. Because of the giant amount of mana you can generate in this deck you can make quite a few hydras. Example; you have a sabertooth, broodmaster, an acolyte, satyr and a nykthos in play. Not too far fetched. Along with, say, 5 forests. You tap out your forests green. Spend 2 on the nykthos and tap it for 6 green mana. You tap the satyr and untap the nykthos, spend 2 and activate it again for another 6 mana bringing your total to 12. You tap your acolyte for another 6. Now with 19 unspent mana you activate your broodmaster's monstrosity ability and put into play 9 9/9 hydras! Doesn't that sound fun?
Karametra's Acolyte: This card is adding more slots of devotion mana-tapping to the deck. It is a step up from the Voyaging Satyr and once you get some green on the field a giant boost to your mana production.
Sage of Hours: This guy is the core of your combo in the deck. Using the bolster effect from the Sandsteppe Mastodon each turn gives this card the counters it needs to give you an extra turn. Other than that, it does not offer much to the deck.
Sandsteppe Mastodon: Another card for the combo in the deck. But a 5/5 with reach is nothing to sneer at on it's own. And you could always end up bolstering up a deathtouch hornet too. But playing and bouncing this every turn with your Temur Sabertooth is how you get the 5 counters on the Sage of Hours each turn.
Temur Sabertooth: The final part of the combo. For 2 mana this cat sends any other creature you have back to hand while becoming indestructible. And this can be used to "rescue" creatures from targeted removal or unwanted auras too. And a 4/3 indestructible creature in play can be useful all on it's own.
Voyaging Satyr: Instead of putting the traditional kind of mana creature in this deck, it uses these cards instead. As long as you have a forest it gives just as much mana as another low cost mana creature. But with a Nykthos, Shrine to Nyx in play this creature can really boost your mana up. The longer the game goes, the more useful it's type of mana production becomes. It is like adding more slots of the devotion land.
The Other Spells:
Beast Within: this card is great in this deck. Not only can you get rid of any permanent for 3 mana which is awesome. But the disadvantage of the card is trivialized by the rest of this deck. Who cares about a vanilla 3/3 when you have 7/7 hydras, indestructible cats and deathtouching flyers?
Commune with Nature: With the combo pieces being creatures this card is an excellent way to find them in your library. Going 5 deep to cherry pick out something you need is super. And you only lose the rest of the cards to the bottom of your library.
Swiftfoot Boots: Spending a total of 3 mana to grant hexproof and haste to any creature in a deck with a combo driven by 3 creatures is perfect. Typically the Sage of Hours would be the best target for this equipment.
The Lands:
Forest: These do what they do. Mono green decks are happy to see Forests.
Nykthos, Shrine to Nyx: This is your really good mana boost in the deck. Once you get this online with a Voyaging Satyr you will generate giant pools of mana depending on what is on the field.
Simic Guildgate: This helps mana fix when you need the blue for a Sage of Hours.
Thornwood Falls: Another 4 sources of blue for your sage along with a free life point which never hurts.
That is it for the deck!
