Of course, like most "destroy an Environment or Ongoing card" effects, it's really difficult to have any idea what it represents. Magic which is equally useful against tumbleweeds and tyrannosaurs is a little hard to picture, even before it starts disarming self-destruct sequences.
Still, it seems like a safe bet to say that the Adept's powers, like those of Doctors Strange and Fate (and also Zatanna, Doctor Voodoo, Scarlet Witch, John Constantine, Circe, Amora, Loki, Doom, Wotan, and roughly every other comic book "magic" character ever) boil down to "omnipotence, limited only by whether I can speak and move, vague references to avilable mystical energy or whatnot, getting interrupted, and arbitray limits which are established early in each story and usually stay consistent until the end of the arc". Which, in gameplay terms, is represented with a bunch of support-based ongoings - that probably even is the role that he plays in team-ups and on the Prime Wardens, but I suspect he does a lot more direct fighting in, you know, his solo series.
This is a tough one, but I think I'll throw in my two cents.
Legacy and Haka are both nearly unstoppable, and aside from the special 'don't-call-it-kryptonite' goo that Baron Blade uses on Legacy, it's not clear either of them can actually be killed. Hell, Haka technically was killed in his bio, and he got better.
Argent Adept and Wraith are both more dangerous the more time you give them to prepare, and given long enough, they can both accomplish almost anything.
Tempest and Tachyon are both very flexible and adaptable, able to quickly and effectively respond to anything the others aren't ready for.
Bunker and Fanatic are both tough and powerful, able to give as good as they get, shrugging off hits and dealing them back out.
Honestly, these teams are actually fairly well balanced. In addition, both teams have a strong, charismatic leader to tie them together (Legacy for the F4 and Argent Adept for the PW). I think this fight could honestly go either way. All eight heros are incredibly good at what they do, it's hard to imagine either side losing.