The X-Men Sealed Pack might well be the most aggressive Sealed Pack format yet. There are quality attack pumps left, right, and center, along with Physical mutants who can attack up the curve without repercussions a fair amount of the time.
By comparison, the defensive tricks are pretty thin on the ground. Genis-Vell ◊ Photon, Transformed is great, and Immovable can cause a lot of sad faces, but there really aren’t many ways of punishing players that are getting a little greedy on their attacks.
So how does this change the way you build decks and play?
First, the Morlock Physical Mutants who cannot be reinforced need to be dealt with very carefully. Formation and reinforcement are important in Vs. System in general, and in Sealed Pack even more so—potentially splitting out the best players. Having characters that your opponent can definitely attack for huge amounts of damage can be quite the gamble. The big question becomes, can you race, when opponents have the potential to reinforce on your attacks, while there are definite safe attacks (from a breakthrough perspective) on the other side of the board? Based on what I’ve seen on the tables today, it seems to be something of an all-or-nothing strategy, which can be frustrated if opponents are playing off-curve. If the pumps are there, though, it is massively powerful.
In terms of playing, one huge difference comes with the choice of initiative. The general consensus here is that the even initiatives are the way forward, as games seldom go to turn 7. Because of the game length issues, 1-drops get slightly better, while the value of 7-drops goes down. Characters like Iceman, Deep Freeze end up being perfectly reasonable (as a 13/13 on turn 6 should be), but a fair proportion of the time, their abilities will not be relevant, as the game will end before they can kick in.
Long story short, odds would be an odd initiative to choose, in most cases.
While playing, it is also worth bearing in mind that there are a lot of pump effects out there, and that it is your responsibility to assume that you will be on the losing end of them. Anything you can do to force opponents to use pumps at suboptimal times (which often tend to be the earlier turns) is probably worth it. Characters like Healer, who on turn 3 stood in front of your 2-drop, effectively giving your opponents no attacks for the turn, shoot up in value as a consequence.
The swings are often bigger in X-Men Sealed Pack. If you can roll with that while opponents are unprepared, then it could be the difference you need to reach the next level.