From the time Theros becomes standard legal I will have two weeks to develop, test, and tweak a decklist for Dublin. This is quite the time crunch, so I have been following the Theros Spoilers very closely and constantly tweaking deck ideas in the meantime. This way when the full set is spoiled, I might (hopefully,) have a finalized idea of a couple starting points in the form of two or three different decks to test.
So far the consensus seems to be that the strongest decks after rotation (at least in terms of what has been spoiled thus far,) are going to be Azorius, R/x (Boros looks particularly primed to be a powerhouse with Purphoros leading the charge,) and Selesnya , with a slight nod to Gruul (almost exclusively because of the power of the color pair’s planeswalkers.)
Today I would like to look at what I might start with as a blueprint for an Azorius control deck post rotation.
Here is an initial list I have in mind:

Azorius Sphere Control

Creatures: (4)

Spells: (30)
Blind Obedience
Sphere of Safety
Thassa, God of the Sea
Celestial Flare
Azorius Charm
Essence Scatter
Sphinx's Revelation
Detention Sphere
Supreme Verdict
Elspeth, Sun's Champion

This list leaves room for 26 lands. Unfortunately, the scry lands for U/W will not be in Theros. The loss of cards like Thought Scour and Think Twice mean that scry is particularly important in this shell because we don’t have any cantrips outside of Azorius Charm to help us hit our land drops. For this reason I include the full four copies of Thassa. I would most likely run 2-3 Guildgates and 1-2 copies of Nykthos, Shrine to Nyx. We should ideally have a high amount of devotion to Blue so Nykthos can let us rip into a pretty powerful Sphinx’s Revelation earlier than would be typical.

The idea behind this deck is to control the early board with enchantments and counters, drop a Sphere of Safety and lock out our opponent from being able to attack us. Multiple Spheres will be difficult to overcome. Our win conditions are Thassa and Elspeth. I originally had Aetherling in mind instead of Elspeth, but on second thought Elspeth seems to fit this shell better. If I can drop an Elspeth and my opponent has managed to remove my Sphere’s, Elspeth, more so than Aetherling, can hold the fort down until I can manage to drop another Sphere or hit a Verdict. Not to mention that Elspeth may be able to supply her own verdict.

I’m not sure that we don’t want some copies of Jace, Architect of Thought in the main deck to help with card draw and devotion, but I’m not positive of what we would need to cut; we want to make sure we have a fairly high number of enchantments in order to let our Spheres get the job done.

The deck seems to be vulnerable to aggressive strategies. The Omen Speakers are helpful and a decent replacement for Augur of Bolas. Claustrophobia and Domestication are going to be leaned on heavily for board control and the double count of devotion they offer, and it’s possible another copy of claustrophobia may need to be in the sideboard for our aggro matchups. Domestication, at least on paper, seems to be really powerful in this shell. If we happen to grab an opponent’s creature that has U in its casting cost that also counts for our devotion, possibly turning on Thassa as early as turn 4.

I’m actually really interested in testing this shell, because I think it may be possible we don’t even need to run Supreme Verdict. If we can control early creatures with Detention Sphere, Azorius Charm and Claustrophobia it might not be needed if we can land a Sphere of Safety on curve. Not to mention if we are controlling the board early with cards like Domestication or Claustrophobia, we’re going to lose the devotion these cards offer if we’re forced to Verdict. This may be the slot where we can fit in 1-2 copies of Jace, Architect of Thought in the main 60 and slide a copy or two of Verdict to the sideboard.

Here is what I might start with as a Sideboard:
1x Claustrophobia
2x Negate
2x Blind Obedience
2x Celestial Flare
3x Daxos of Meletis
2x Jace, Architect of Thought
2x Gainsay
1x Bident of Thassa

Here I want to tailor my board towards aggro and a U/W or U/W/x shell.

Against aggro we bring in the extra Claustrophobia, Celestial Flares and the copies of Daxos. Daxos will let us remove their threats while gaining life, allowing us to hopefully stay above water until we can drop a Sphere of Safety.
Coincidentally I feel Daxos is also great in the mirror match or against midrange strategies (where we might also bring in the Bident to let us get some card advantage.) If the meta slows down as much as people would have us believe (of which I’m fairly skeptical,) Daxos might end up being one of the major players in the new meta. He also happens to play nice with Thassa, which is a nice bonus.

Against the mirror we want to side out the copies of Sphere of Safety, Domestication, Essence scatter and Verdict. Let’s bring in 2x Blind Obedience (we’re playing for the long game, and extort triggers can work wonders in the mirror,) 2x Jace, 3x Daxos, Bident of Thassa, and 2x Gainsay. I like to leave the miser celestial flare in the 60 as a way to get rid of an opposing Thassa, Heliod, Daxos, etc. The tempo swing that can offer in such a matchup can be pretty powerful and many people will assume you will side it out.

My sideboarding against other midrange strategies might be similar although I would side Negate instead of Gainsay, and depending on what these decks look like maybe leave some copies of cards like Domestication, Sphere, or Verdict in the deck.

This is a very rough first draft of this deck list and I look forward to updating it as more Theros spoilers are revealed. I’m also looking forward to working on some other decks in the next few weeks to get ready for the exciting world of new standard!