So, this deck is essentially a flicker control deck. The idea is to really start going to value town with this synergistic combo turn 3 and beyond. You just gotta make it to that point by using stall spells for a few turns.
The deck is a little slow sometimes. I'll often be at 10-15 life with no spells played by turn 3. Once I hit turn three I can turn the corner very fast.
T1- Play a land. Since there are not many one drop spells in this deck (other than Path to Exile, Condemn), Spell Snare and Cloudshift it is best to bring in a hallowed fountain tapped, or a colonnade. If you are on the draw and you have spell snare in hand sometimes it is best to play an island and pass.
T2- Statistically you will usually have a Wall of Omens or Path to Exile in hand on turn two. If you have the wall, generally just play it without question. This is the main engine for value in this deck so it is imperative you play it asap. Turn two is ideally the curve you want to be playing this card on. If you see a Viscera Seer, a Lord of Atlantis, a Steel Overseer a Tarmogoyf etc or some other very threatening creature it may be good to play the Path to Exile on their turn and just bring in another Celestial Colonnade tapped.
T3- Now you can finally start doing stuff. I almost ALWAYS play a hesitant defensive game. At this point I will probably be dropping my first Detention Sphere, or using a Vendilion Clique on their end step to make sure they aren't up to something. If they STILL haven't played a spell at this point and I have the Spell Queller I am nearly 100% of the time going to flash it in on their end step....I could see how this could be considered a weird play, BUT IT IS ALWAYS GOOD TO GET IN BEATS EARLY. Plus you can always flash in Restoration Angel or Cloudshift later on to flicker the Spell Queller to exile a spell on the stack. Start getting in attacks early could just clench you the W. BE SMART. If they are playing blue and are untapped often times it is good to bait a removal spell or counter spell with Spell Queller or Vendilion Clique at their end step so you can main phase your 4 cmc creatures without fear of repercussions. Another good play is to blow up Field of Ruin depending on the situation i.e. they have a manland out or you need 3 blue for Cryptic Command.
T4- Again play defensively, know when to use Venser, Shaper Savant Don't just randomly play him on your turn if you don't have to. It is imperative to know how and when you should use this guy. He has flash so most of the time I will end up waiting to see what they do on their turn to decide if I want to cast Venser, the Restoration Angel, or just use a Cryptic Command. There are multiple lines of play, just make sure to play smart. If they have a wall of creatures out with 3 out of 5 of them being the same creature use a Detention Sphere, it is always fine to hold a mana up on turn 4 to either bait them with Path to Exile mana or just play another tap land. Turn 4 is the trickiest turn of the game. Sometimes it feels right if they are tapped out to main phase a Restoration Angel to hit a Wall of Omens, sometimes it is better to play a Wall of Omens and hold up 2 mana for a Negate on their turn. It is imperative to always be 2 steps ahead of your opponent. get inside their head, bait them with cryptic mana even if you don't necessarily have the Cryptic Command in your hand.
T5- At this point you're generally going to want to cast your plansewalker if the board is clear(ish) even if you have nothing to flicker him with. his ult is backbreaking enough that even if you are just +2 on a land it is scary. If he resolves and you have a Wall of Omens, Venser, Shaper Savant, Vendilion Clique etc you are in good shape and will generally out value them. If you have a Restoration Angel out always attack with the angel and then flicker the angel to reset it as a blocker with Venser, the Sojourner, once the angel comes back in you can re flicker a wall of omens, etc. The other alternative is Lavinia of the Tenth. I can't tell you how many times I have been mocked for mainboarding this "non competetive junk rare" just to softlock most of the modern meta out of the game completely. Pro red is more relevant than you think and when you get her out with venser, it is hell to get through this duo. her ERTB ability hits Artifacts, creatures, and even plansewalker, (I am looking at you Koth of the Hammer and Liliana of the Veil. Play a game of good control and there is no reason why you shouldn't walk out victorious.
All cards have synergy with the captain of the deck Venser, the Sojourner
This deck does incredibly well in competitive play. While it is a little costly, it gets the job done. Let's take a further look into the decks synergy and cards.
Spell Queller- this standard card caught my eye at the pre release and I can't help but play a playset. It almost seems like Spell Queller and Lavinia of the Tenth are a match made in heaven. (Assuming they are playing 4 mana spells ;) YOU CAN FLICKER THIS WITH RESTORATION ANGEL TO DO SOME REALLY WEIRD COMBOS. This card is broken, it gives tempo, it's everything blue white should be about. It also gets around Cavern of Souls text and Boseiju, Who Shelters All.
Wall of Omens- Fairly obvious why this guy is in the deck. 2 mana to bring out a defender while you wait to bring out the stompers of the deck, and net a card repeatedly with Venser.
Snapcaster Mage- I only run two of him, mostly because the instants I do run are fairly high costing in mana, so running more than one is generally not that helpful. However, flickering him for a couple of path to exiles is always quite a silly thing to do.
Restoration Angel- Fits the theme of the deck, obviously. She buys me time, synergies with the deck, and packs a punch in the air. It's a win win.
Vendilion Clique- Awesome card in modern. Interrupts tron combos, splinter twin combos (RIP), kitchen finks combos, etc etc. blink this dude for continued abuse on your opponent so they never see their combo any play. Can even flicker Clique and target yourself to draw a card if you are fresh out of a hand.
Venser, Shaper Savant- By far my most favorite card of the deck. Flash this guy in at the right time to to remand a spell. Turn 5 bring in Venser, the Sojourner and go nuts. Return lands, return creatures. Do what you want, he is definitely the star of the show.
Lavinia of the Tenth- The CHEAPEST card in the deck. Oddly enough, this card is SO good against red decks, and pretty much any deck that runs low costing creatures (Oh wait, I think I just named half of the modern meta). I am looking at your Tarmogoyf. blink her in for continued detain and watch your opponents face turn from "wow,. look at this dumbass and his dollar rare....4 turns later the softlock with venser and lavinia is enough to make anyone hate you. Either keep detaining by blinking her to ultimate the plansewalker, or if you feel that you have enough creatures out for a win, use Venser, the Sojourner -1 ability and make them unblockable for an easy win. This card rules, seriously.
Detention Sphere- You can actually blink this enchantment with Venser. So NASTY.
The instants I run are fairly standard modern control staples. Use them wisely, and remember, you can ALWAYS Path to Exile and Cryptic Command bounce your own creatures to net a land or grab another ETB effect.
Celestial Colonnade is an alternate win con, for when both players start top decking, or I am just trying to beat them down quickly.