Sun Titan will be the best creature in a month.
Honestly it might not even take that long. This week I played against Brad Nelson for our playtesting series. Both times he used Sun Titan decks and while both were vastly different his decks performed admirably. Had they been built correctly they would have done even better.
Here's a list of things that Sun Titan can do for you:
1) Bring back a Phantasmal Image copying Sun Titan. Maybe some decks have an Oblivion Ring or Liliana of the Veil they wanted to use to kill your Titan but that almost never works. Sun Titan typically brings another copy or two of himself in addition to all the other insane things he does for you. It's probably not even necessary to copy Sun Titan in order to win but it locks the game up.
2) Bring back a Ratchet Bomb to finally reduce a Delver player to dust. Have you have ever had that game as a control deck where you've been grinding the best you can but they have Moorland Haunt or peeled a Lingering Souls? Delver can actually grind out control decks with those cards and nothing short of Curse of Death's Hold can really save you.
Enter Sun Titan for Ratchet Bomb. Most of the time that's the play that seals the game up. Whether they finally stuck a Geist of Saint Traft or were about to equip a Sword of War and Peace to a token or had two Insectile Aberrations coming at you infinity Ratchet Bombs is there to save you.
3) Bring back an Oblivion Ring to deal with their Sorin that is about to ultimate.
4) Bring back a Ghost Quarter so you don't die to Kessig Wolf Run Inkmoth Nexus Gavony Township or Nephalia Drownyard. You can Oblivion Ring and Ratchet Bomb everything else but the spell lands are tough to beat.
In order for Sun Titan to accomplish 1-6 you need to do a few things. First you need to play those cards in your deck. That might seem pretty obvious but once you play Phantasmal Image Ratchet Bomb Oblivion Ring and some stuff to draw cards and filter through your deck you don't have much room left. Since my deck is based on finding and resolving Sun Titan and making it good in the first place I think I'm ok with that.
Second you need to slow them down or accelerate yourself. Against Wolf Run Ramp you can usually cast a Titan after they've cast a Titan and still be fine. However a turn or two later and Sun Titan might not dig you out of that hole. Similarly with Delver you need to have killed off a few of their threats. You can't expect Sun Titan to beat a flipped Delver Geist of Saint Traft Sword of War and Peace and a Snapcaster Mage in hand all by itself.
Just help him out a bit and he'll take care of the rest.
The way I see it you can go down one of two paths. Traditional Esper Solar Flare is the first and the second is Five-Color Control. Of these you might think that I'll blindly choose Five-Color Control based on the fact that I previously championed that deck while constantly hating on Solar Flare. However it's not that cut and dry.
Both have their distinct advantages. Solar Flare's mana base used to be an abomination with a menagerie of Scars lands and M10 duals. You'd have all these dual lands yet not be able to cast your spells and even when you could the majority of them would enter the battlefield tapped.
That's just unacceptable. Evolving Wilds fixes Flare's mana base to an extent but so does not being greedy. Liliana of the Veil while very powerful is typically the black card that stretches your mana base to absurd proportions. On the other hand Mana Leak is the card that makes you need heavy blue requirements as Leak is only good early.
My solution is work on your mana base to the point where you have enough duals that you can realistically cast your spells. You should also choose whether you want to be base W/B splashing card drawing or U/W splashing removal and flashback.
For example if you're base U/W splashing Forbidden Alchemy Lingering Souls and Unburial Rites you don't need Darkslick Shores. Sure if you go Scars land into Scars land into basic into M10 duals for the rest of the game you're set. However you could just as easily go M10 dual into M10 dual into basic into Scars land Scars land and be behind the entire game.
Early on you probably need blue for cantrips and Mana Leak whereas you need white for Oblivion Ring and Lingering Souls. You won't need your black sources until later but when you do want them you want them to enter the battlefield untapped. For this reason I'd recommend using a lot of Seachrome Coasts and more M10 duals that provide black.
Five-Color Control has a terrific mana base despite what you may think. All of its mana requirements are single (until you're casting Sun Titan of course) and any U/W dual and a Blackcleave Cliffs fixes your mana. Recently with the addition of Faithless Looting and a lesser need for Mana Leak the mana base has gotten even better.
Mana Leak kind of stinks right now at least in Sun Titan decks because you don't need a catchall. You have specific answers to nearly everything and whatever you can't answer you can probably beat with Unburial Rites. With that requirement out of the way you're free to do whatever you like mana base-wise.
Brad has written plenty about the deck here so you should check that out. I'd like to say a quick few words though. There are a couple of things I would tweak in Brad's list such as the mana base. I would also play the fourth Desperate Ravings probably over a Tibalt.
Playing a narrow card like Ancient Grudge might not seem correct but you have Faithless Looting. The way the games play out you almost never flash back every single card in your graveyard by the time the game ends. You always have plenty of gas which means there's no shortage of discard outlets for Ancient Grudge.
Be wary though; I had this situation come up in my playtesting session with Brad:
I was playing U/W Delver and Gitaxian Probed him early looking for action and saw two Lingering Souls. I Dissipated the first one (HA!) and he declined to cast the second one on turn 4. I thought this might be a mistake since if he waited a turn I would be able to play a land and have Snapcaster for Dissipate. In the end I didn't draw a fifth land but he didn't cast Lingering Souls anyway. He was biding his time building his mana base and attempting to play around Mana Leak.
A couple turns later he cast a Faithless Looting going up to six cards. He almost instantly discarded an Ancient Grudge and then later discarded a land. The game went on for a few more turns and I was finally finding some action. We fought on his turn over a Geist of Saint Traft which I successfully protected.
With him having Blackcleave Cliffs Copperline Gorge and Shimmering Grotto untapped I saw a window of opportunity. I could very easily cast and equip Sword of War and Peace while also protecting it from Ancient Grudge with Mana Leak or Negate. I felt like if he had just the one Grudge he would probably take the hit down to nine or so and then main phase Grudge to play around Mana Leak.
Wait a second though! What if he had more than just the Ancient Grudge in his graveyard? He discarded the Grudge almost immediately which granted could have been a bluff that he had an extra Grudge. In my mind that registered as "I have this Grudge but definitely don't need it in my hand." There had to be a reason Brad felt he didn't need that Grudge and I thought it was because he had a second one.
As Michael Jacob later pointed it if he had two Grudges he would've just discarded them both but I don't think that's true. My rationale thinking from Brad's point of view was that he didn't want to cast Lingering Souls into a potential Dissipate or Snapcaster Mage into Dissipate.
He should probably know that I'm playing draw-go because I have a fist full of permission. If that were the case he couldn't afford to just discard one Grudge because it would get countered and he'd lose to the Sword. I had Moorland Haunt going too so it's not like he could just Phantasmal Image the Geist and get out of it.
Discarding both Grudges means that he might end up bottlenecked on green mana with only a sole Shimmering Grotto as I don't remember if he had the Copperline Gorge yet or not. Regardless if I were in Brad's shoes and had one Grudge I wouldn't discard it. If I had two Grudges I would probably keep one instead of my seventh land especially since I had more card drawing in the graveyard to find lands if I needed them. However Brad might have thought that since he had more card drawing he could find more Grudges.
My only logical conclusion was that Brad had a second Ancient Grudge my Sword was virtually a dead card and that I should proceed as such. Now if my hand was worse I would probably shove on Sword and just hope that he made a mistake but my hand was actually fine. I just ended up flooding out while he constantly had gas.
By the end of the game he still only had that one Grudge though. I guess I gave Brad too much credit or we would just play differently in those spots but it cost me the game.
Mostly that tangent means that Sword is a very dangerous card and you should play around it if you can but it also means that yes Ancient Grudge is worth splashing.
Here's what I think we need in Esper Solar Flare:
3 Sun Titan: This is your end game and you want to draw into one in a reasonable amount of time.
3 Phantasmal Image: Even if this were a Sakashima the Imposter you would still play some number for the combo with Sun Titan. The fact that it kills Geist of Saint Traft one of your biggest enemies is reason enough to play three.
1 Elesh Norn Grand Cenobite: Elesh Norn trumps most strategies so I feel like playing one is probably right. It stops most of what Wolf Run Ramp is doing whereas Sun Titan with a naked graveyard probably won't. With at least one Unburial Rites in the deck you should play one.
1 Unburial Rites: You could go harder with Liliana of the Veil or incorporating Faithless Looting but you could just wait a few turns and cast Sun Titan. That plan might be even better now with a couple Cavern of Souls.
4 Forbidden Alchemy: Without red you need to play the max amount of Alchemies for Sun Titan and Unburial Rites. One of the best parts about the Five-Color Control deck is you never run out of gas. With Solar Flare that's a distinct possibility since Think Twice is half as good as Desperate Ravings. At least with Forbidden Alchemy you can hopefully chain them and keep the engine going.
2 Oblivion Ring: This is kind of slow and unwieldy but it's necessary. If they get to Titan you first it's pretty important to either Sun Titan into Phantasmal Image or Oblivion Ring to maintain parity. It's also your maindeck answer to Swords aside from the Titan/Ratchet Bomb soft lock or quickly ticking a Bomb up to three.
3 Ratchet Bomb: Kills tokens transformed creatures Oblivion Rings and planeswalkers in a pinch. Sometimes you even get to trade with a Sphere of the Suns which turns your dead card into a real one. Three seems like the best number since you want them early but don't necessarily want to draw multiples.
2 Ghost Quarter: This is another one of those cards that allows you to Titan after they Titan and still have a shot.
2 Cavern of Souls: A resolved Sun Titan is great against Delver but only if you can survive long enough to play it around Mana Leak. With Cavern you can probably just slam Titan on six some of the time bring back a Ratchet Bomb and win the game.
So far I've been very impressed with Cavern of Souls in Titan decks which you can see in some of our upcoming playtesting videos. The card is the real deal and forces Delver to adapt or die. I'm not sure if I could incorporate Cavern into the Five-Color Control deck although I'm guessing not. For Solar Flare though it's an auto-include.
Here are some things you could play but don't necessarily have to:
Mana Leak: This is like an Oblivion Ring that interacts with the stack. It's not a great card and it's not going to wow anyone but it does its job. That said you can certainly cut it because you have enough permanent answers as it is.
Negate: With Cavern of Souls making Mana Leak a little less good I could easily see a Negate or two instead of Mana Leaks. While you won't be able to counter that Huntmaster of the Fells or Geralf's Messenger you can still stop Swords and Planeswalkers which are the hardest cards to beat.
Think Twice: This one isn't necessary either. Its effect is so minimal on any given game that it might actually be a detriment to your success. Five mana over the course of two turns might not seem like a big deal but you're often on the back foot. With a Think Twice stranded in your hand your options are limited even further. On top of that getting flooded with card selection spells and not enough action is a real problem sometimes. There are other options for card selection.
Thought Scour: For those that want to turbo-charge their Sun Titans and maybe play a second Unburial Rites there's Thought Scour. I'd say the deck doesn't have enough extra blue mana lying around in the early turns to make this worth it. However if I were in the market for something costing one blue it would be...
Ponder: I like this more than Think Twice. One mana versus five is a huge deal and now you have Evolving Wilds to shuffle every once in a while. MJ and I have played two Ponders in U/W/R Control and Five-Color Control and been very happy with them but I've also played them in a 23- or 24-land Esper Control deck with Sun Titans.
Finding a single card you want setting your draws digging for lands or shuffling away a clump of lands are all very powerful things for a one-mana spell. Ponder is better than Think Twice even if it's not "card advantage." Things like costing 4/5ths less matter far more.
Haunted Fengraf / Unhallowed Pact: These are cute ways to fight removal but they don't work out how you want them too. There's always random Phantasmal Images chilling in your graveyard and Pact basically only works against Day of Judgment. If they have an instant speed removal spell they'll just hold it up when they see the Pact in your graveyard. You can get some value by playing it on their Primeval Titan and then casting Day of Judgment but in the end Phantasmal Image will be better the vast majority of the time.
Snapcaster Mage: Snapcaster Mage is a good card but he's only as good as the cards he's flashing back. In Solar Flare you don't have many good cheap options. That makes Snapcaster Mage slow and ineffective. The 2/1 body is also irrelevant.
Hopefully with all this information you could build a list yourself but I'll show you what I came up with:
I'm not playing any planeswalkers maindeck because I don't think you want to. Your goal at least in game 1 before graveyard hate comes in should be on making your Sun Titans as good as possible. Post-board against control decks they'll likely have some number of Surgical Extractions or Nihil Spellbombs. While it's not backbreaking it just means you can't rely on Sun Titans.
I really like the Intangible Virtue sideboard plan against aggressive decks like G/R Aggro and Zombies. Virtue into Timely Reinforcements is often better than casting a Sun Titan against them anyway. Virtue also gives you a threat against control blanks their Curse of Death's Holds and allows you to efficiently attack their planeswalkers. Basically Virtue is awesome if you have six token makers and some card selection because it fights them on another angle.
This week I'm testing for the Block Pro Tour in Barcelona so I won't be making it up to Providence for the Open Series but I wish I could attend. I want to see Cavern of Souls being put to use in both Standard and Legacy and I want to see if anyone has any sick Legacy brews with the miracle mechanic. As usual the event will be covered by SCGLive so I guess I'll have to get my fix there.
Depending on how things shape up from that tournament and the tournaments to come I could easily see myself shelving my Delver of Secrets and picking up Sun Titans. It seems incredibly well positioned again and it's been a while since I've played a good control deck.