Over the weekend, spoilers were light - they've started back up today (aka last night at midnight Pacific time), and here's a few I'd like to mention: Tajic, Blade of the Legion
I feel that this *could* potentially see some constructed play - given that he's an indestructible 2/2 for 4, he's definitely more of a mid-range card. But his Battalion ability has some interesting advantages, especially when you also have Frontline Medic on the battlefield (which already sees play). This guy will definitely be a limited all star, if nothing else.
While a 6-mana clone card isn't exciting by itself, this particular one has an interesting upside: if un-dealt with, this Shapeshifter will continue to replicate turn-after-turn. And, unlike Stolen Identity, you don't have to be aggressively attacking to get there. I can definitely see this getting played in constructed. (Is this the Biovisionary combo Johnny has been waiting for?)
It seems that Wizards thinks Mana Drain is too powerful for standard - I think they're right. This seems to be much more fairly costed, and also makes you wait until your next precombat main phase (where Mana Drain simply says "next main phase"). The only thing holding this back from seeing tons of constructed play is its GGUU cost, but the amount of dual-lands that are currently standard-legal will definitely help. Prime Speaker Bant decks that focus more on control will definitely like cards like this.
Update @ 1PM Eastern: Looks like a couple more cards leaked since I wrote this, and I like both of them (so I'll talk about them below).
A cheap enchantment that's FULL of text, and is playable? Okay, I'll bite. Obviously the power/toughness buffs aren't irrelevant, especially if the board is full of 3/3's on both sides (this kind of card can help break stalemates). The activated ability (for two mana) essentially makes your entire line of creatures invulnerable to Bonfire of the Damned, Terminus, and Supreme Verdict (among many others). Having to float two mana in order to use this ability isn't too much to ask, and this card will definitely create some interesting interactions. ALSO, the fact that the creatures come back at the beginning of the next combat phase means you likely won't die from an alpha strike by your opponent. I'm no expert on older formats (I haven't even technically played Modern or Legacy), but I have a feeling that this will see play there as well as standard, given the low cost (and high upside). Great card.
At first, this card reminds me of Primordial Hydra - and I think R&D might have wanted to create a similar card, with flavor that more closely matches the red/green color combo (and the Gruul guild, in this case). Upon further inspection, this card seems much more likely to see play in constructed - anything with double strike pairs very well with Ghor-Clan Rampager (which sees quite a bit of play). One interesting note, though: I feel like since the ability to add counters uses hybrid mana, maybe the cost of the card should've used hybrid mana as well. The only downside to that is that the card *might* be too good, since it could be shoved into mono-green or mono-red decks - but those don't see too much play anymore (given the current land situation).