Crested Sunmare - $4.99
Crested Sunmare looks like a pretty narrow casual card, but might it actually be…a Horse of a different color? (Okay, that was really bad. I'll stop.) If you can gain life on the same turn you cast this, Crested Sunmare does a pretty decent Wingmate Roc impression—no evasion, but getting a pair of beefy beaters that don't die to most of the format's spot removal is pretty spicy.
The problem right now is that I can't really see the right lifegain card to pair with Crested Sunmare, nor do I think it's good enough to spawn an entirely new strategy. Chances are, it ends up in the $2 range over the short-term as nobody is able to find a way to slot it into a solid competitive shell. Keep an eye on it, though—if the next block provides the right support, you may need to pony up some real cash to grab your playset.
Majestic Myriarch - $3.99
Full disclosure: I'm a little lower on Majestic Myriarch than I probably should be because I really don't want to have to learn how to correctly spell "myriarch" for a bunch of future articles. That said, I really don't see a world in which Majestic Myriarch sees much competitive play. Worst-case, you've just paid five mana for a 2/2. Best-case, your army of creatures with a million keywords is good enough to win without Majestic Myriarch. This is also the kind of card I tend to cut from my Commander decks because it doesn't really synergize with anything—it's just kind of big. The art is cool, though. Future bulk mythic.
Hour of Devastation - $2.99
Awesome. Hour of Devastation is the Hour of Devastation card that's most likely to shake up Standard, and it's not particularly close. Five damage kills darn near everything, and the fact that this can hit planeswalkers makes it a sight better than Fumigate. Mardu seems like it will be hit particularly hard, and I suspect that some version of Grixis or Jeskai Control will emerge. The current version of U/R Control should get a major boost from Hour of Devastation as well.
Financially, I see no reason not to buy a set of these for $3 each. The card will see play, probably in multiple Tier 1 decks. I expect it to end up in the $5-$6 range, but it might spike even higher in the short-term. Worst-case, current retail is pretty close to Hour of Devastation's floor.
Abandoned Sarcophagus - $1.99
I've talked about "combulk" before, and Abandoned Sarcophagus has a shot at being one of the best. There's a shot that it ends up enabling a deck in Modern or Standard right off the bat—Drake Haven would almost certainly be a part of that strategy, so it's the buy if you're a believer. More likely, though, Abandoned Sarcophagus doesn't find the right home and it ends up dropping into the bulk rare range.
That's when it's time to buy. Abandoned Sarcophagus oozes with the kind of potential that will cause a spike the next time Wizards of the Coast announces a cycling card of any kind. You won't even have to wait and see if the combo works—you can just sell into the hype. Short-term, I'm not quite sold. Long-term, I want a stack of these.
Leave // Chance - $1.99
I'm not sure what deck in Standard will want Leave // Chance, but it might show up in an older format. Puresteel Paladin decks might want this alongside Retract, and it might even be good enough for Mentor decks to consider in Vintage. I can't justify buying in at $2 unless someone can give me a feasible way that Leave helps a deck in Standard, but foils seem like a decent flier if they're under $5, on the off-chance that this becomes a solid role-player in some Eternal format.