Welcome back speculators!

I realize that Born of the Gods doesn't officially release until February 7th, but now is a great time to start preparing for it. "But David the spoiler is basically nothing," you say, "all we have spoiled is three scrylands."

That's important information. It means that there will likely be a resurgence of multicolored decks again. There are a lot of rumors about multicolored gods, which will likely mean multicolor devotion requirements (either two abilities or two requirements), but it would likely spawn dual colored devotion decks.

What that means is that there will be possibilities for all the strong hybrid colored cards to break out (similar to Nightveil Specter). While it's not that likely that either the Specter or Boros Reckoner will spike much higher than they currently are, there is lots of opportunity for the other dual devotion enablers. I will list them below and rate the likelihood of a breakout from 1 (low) to 5 (high).

1. Cryptborn Horror (3) - This guy is actually relatively aggressively costed. The obvious downside is that he (like Rakdos himself) can't be cast if you haven't damaged your opponent, but mid- to late-game he can be a huge threat with built-in trample. This seems like one to pull from the bulk boxes just in case.
2. Growing Ranks (2) - This one was popular with the casual crowd when it first came out and many players expected tokens to be a deck. It hasn't panned out and unfortunately, the token strategy doesn't appear to be a big concept in Theros block. It does have some good synergy with Heliod (it provides two devotion and can populate the tokens he creates).
3. Nivmagus Elemental (2) - This one was hyped for combo style decks, but it too never panned out. The fact that it barely enables devotion puts it into the unlikely-to-break-out category.
4. Rubblebelt Raiders (3.5) - I think this is the card most likely to break out. The ability is quite powerful and most importantly it provides three devotion to two different colors (similar to Boros Reckoner and Nightveil Spectre, the two best devotion enablers).
5. We will ignore Deathrite Shaman, Boros Reckoner, and Nightveil Specter for now as these have already spiked, and while there is room to grow, the highest gains I think we can expect are 40%-60%. It's also interesting to note that there is no Orzhov permanent (they got Immortal Servitude instead).

The spoiling of three new scrylands (with strong expectations that the remaining two will also be in this set) will allow players to go back to playing three-color decks with almost perfect manabases (albeit slower ones). This will push the shocklands back up. This will likely mean a few shocks over $10 while the rest stay in the $7 range.

My guess would be Watery Grave and Temple of Deceit as the best ones at first, but I wouldn't count out a Naya aggro deck making a comeback, as its card base is strong and efficient and those decks prey on the slower more linear decks.

Should the format indeed revert back to multicolored, then it's also highly likely that Mono-Red will be the best deck for the first few weeks. The fact that the scrylands always enter tapped means that the 3+ color decks will be slower and vulnerable to aggressive burn decks.

This means that mono-red rares and mythics will likely get a resurgent bump in price. Here are the cards to watch out for:

1. Ash Zealot - Currently sitting in the $2-$2.50 range, thus guy could easily spike back to $5 for the first couple of weeks, especially if he gets some help from Born of the Gods. The fact that he's a regular rare in a heavily opened set keeps the ceiling around $5. This means the risk of him not spiking may not be worth it to those of you who go for the "Babe Ruth approach" (home runs or strike outs and little in between).
2. Stormbreath Dragon - Currently sitting in the $18-$20 range. He is less likely to break out in a faster aggro deck as those decks tend to skimp on their land count and 5+ drops are usually two-to-three-of's at best. Given his current price I see a max potential of $30 which is only a 50% price jump (not bad, mind you), but if you can't unload him while he's hot you'll likely miss out on most potential profits. It doesn't help that black is so heavily played right now as every kill spell they have hits Stormbreath.
3. Chandra, Pyromaster - Currently you can pick copies of her up in the $14-16 range, which is about where she started. I think she's a solid pickup and has shown the ability to jump to $40+ when she's hot. The fact that she comes from M14 (which is already a lesser opened set) gives her a lot more potential. I like getting these at their current price, especially with her multi-format and archetype playability.

A resurgence in 3+ color decks will also trigger a stronger demand for the color fixers and mana rampers. Sylvan Caryatid and Mana Bloom at rare show strong potential. (Prophetic Prism is another way to do this, which, while it doesn't ramp, does fix.)

1. Sylvan Caryatid - Currently priced in the $4.00-$5 range, it could go up to $8-9, but it's unlikely to go much higher. I personally see Carytid as the way to go. It also serves as a good defense against many of Mono-Red's early creatures.
2. Mana Bloom - This is your "go for the fences" card I think. It's an enchantment (so more difficult to get rid of) in a supposedly enchantment-themed block that fixes and ramps and is currently a bulk rare. I personally think this is the card most likely to increase 400-500%, though that still only means a jump to $1-$2.