These are two more mythic rares, and give us a total of 3 mythic rares dedicated to Zombies; and one of these, I’m slightly disapointed in, and in the other one I’m rather impressed.
Grimgrin, Corpse-Born, is an impressive looking legendary creature card, a 5/5 for 3UB, and something about +1/+1 counters. Also, he’s a warrior, so that’s cool, and gives us a black and blue zombie general for Commander! But he enters the battlefield tapped and doesn’t untap during your untap step. Mark Rosewater said this would be a theme with these zombies; saying that they have to be slow. Which he certainly is, especially for a card that’ll just get dismembered if he hits the board before he gets to eat another creature; which is his first ability; you can sacrifice another creature to untap Grimgrin and put a +1/+1 counter on him. It’s an interesting engine, which fuels the other zombie sitting next to Grimgrin up there. However, he also has an attack trigger; when he attacks, you destroy target creature the defending player controls and put another +1/+1 counter on Grimgrin. With an engine to utilize with him, like Bloodghast (or something similar in this set, hopefully) he could be extremely powerful, and would be very good if Bloodghast was staying in Standard. Regardless, unless your opponent has Dismember, he could cause some serious problems. Then again, his death could benefit another zombie…
Skaab Ruinator is a 5/6 flyer for 1UU, which is pretty good, right? Well, you also have to exile 3 creatures from your graveyard, which isn’t too bad. It’s possible zombie will end up playing UB with Liliana the Veil to discard and hopefully nuke an opponent’s board. But the greatest part about Skaab Ruinator? You can cast him from your graveyard. So you could remove those three creatures very, very late game to drop this 5/6 on the board again for 1UU. I really like this card, but I hope that Innistrad has some way to put cards back into the graveyard to keep us from completely running out of fuel, maybe a card that says “sacrifice target zombie you control; send creature cards that are exiled equal to the colored mana cost of the sacrificed creature” or something along those lines. In my opinion, Skaab Ruinator is much better than Grimgrin in comparison of both of them being mythic rares.
But Zombies aren’t the only mythics here; Essence of the Wild is a card that even Wizards admits is a little silly; creatures you control enter the battlefield as a copy of Essence of the Wild. Birds of Paradise? Nope, 6/6 Essence of the Wild. Darksteel Myr? Nope, Essence of the Wild. Batterskull with a 0/0 germ? Nope, 10/10 with vigilance and lifelink. It’s a pretty silly card, but it’s not really great. It could be a bomb in limited, but otherwise? Not all that great. It may see play in Birthing Pod as Daily MTG suggests, as 6/6 Birds of Paradise can always be fun.
However, outside of the mythics, we’ve got a couple of uncommons, and so we see Into the Maw of Hell, which for 4RR destroys a land and deals 13 damage to target creature. 13 damage! As Mark Rosewater pointed out, 13 is a theme in the set, so if it’s gonna over kill something, it’s gonna say 13 on it. If Ludevic’s Abomination is a big worry for you, don’t worry, Into the Maw of Hell has you covered.
I’d be excited for this if it wasn’t a 5-drop. 3BB gives you a 4/4 with a morbid ability; when it enters the battlefield, if a creature died, target creature gets -4/-4 until end of turn. It’s a mini-dismember on a 4/4 stick for 5. If it wasn’t yet another 5-drop it could see play in Morbid Pod, but it doesn’t look like Morbid Pod will ever happen, as they haven’t printed enough playable morbid cards for it yet. If this was a 4-drop it’d be perfect.
However, that’s all the spoilers for now, I will, of course, put up spoilers as I find them.