Based on Jacob Van Lunen's "Captain Crunch" deck first previewed here: http://www.channelfireball.com/articles/valuable-lessons-valuable-lessons-standard-has-a-real-combo-deck/
This deck is a one-trick pony, but it's a pony that'll win the game for you in one round if you can get the right cards in your hand.
You start by getting as many mana dorks out as you can. In this case, there are full playsets of Elvish Mystic, Voyaging Satyr, Rattleclaw Mystic, Sylvan Caryatid, and Kiora's Follower. Additionally, a single Golden Hind is thrown in for good measure. You want enough mana-generation capability outside of lands that you can cast any of the card-drawing spells with it (except maybe Plea for Guidance). You also want to have more dorks on the board than your opponent has creatures, if possible (may be unfeasible against token generator decks and other really fast aggro).
Once you have sufficient dorks (aim for 4+) in play, a Jeskai Ascendancy in your hand, at least one other card draw spell in your hand, and you're still in the first main phase of one of your turns, play the Ascendancy. For this play and all future plays this turn, you want to use creature mana whenever you can and avoid using up your lands if possible. With the ascendancy down, you start the combo process:
Play a card-draw spell using creature mana. Ascendancy will cause the dorks to untap and to gain a +1/+1 counter. You now have new cards and your mana dorks are ready to provide more mana. Repeat. Keep Repeating until you have enough +1/+1 counters on your dorks to be lethal to your opponent, then declare attacks.
Some notes based on playtesting:
You don't want to start the combo until you have the ability to cast a second Jeskai Ascendancy just with creatures (or using your Voyaging Satyr or Kiora's Follower to untap lands). Getting multiple Ascendancies out is key to really ramping your temporary dork power through the roof.
Once you play the first Jeskai Ascendancy and start the combo, don't play any more creatures... they won't be able to attack this turn even if they are +20/+20. If you have creatures or land in your hand, use them as discard fodder for the Jeskai Ascendancy draw/discard trigger.
If you find yourself with a Plea for Guidance in your hand and enough mana to spend it, use it to pull two more Jeskai Ascendancy cards into your hand.
Any additional Jeskai Ascendancy cards after the first one should be played as soon as you can because they'll stack for multiple +1/+1 pumps per spell cast afterwards.
In general, this deck operates too slowly to be reliable against a fast opponent. Occasionally the draws don't go your way and you end up starting the combo but running out of draw cards to play before your attack is lethal.
The deck also suffers from one interesting weakness in the form of Deflecting Palm, in that if you pump your dorks up to the point where their power is greater than your life, and then attack and someone deflects one of them, at a minimum you are dead and at best it's a draw game.
