Mr. Freeze's Gun
Relic 5-6

Character can use Barrier. When it does, it can use Incapacitate as a free action targeting all opposing characters adjacent to a terrain marker placed by this character.

Magneto prime can use barrier through a special power, does this mean that he can't use the effects of Mr. Freeze's gun?

Correct.

/filler

Unfortunately, Magneto is not that cool.

Chill out.

Ooohh BURN!