This card is very thematic but I'm unsure of how much I will enjoy it due to being frozen the next turn. It does seem very powerful still and it may be a very strong character to build around. I am very interested in what the rest of the set has in store.
Getting an "Earth's Mightiest Forces effect" for a fortress is very strong. I'm worried that the freeze will slow the deck down to much but then again only a few cards of the set have been spoiled so far. I could see the deck being an aggressive deck, but to keep that aggression up would be a little more difficult over a standard aggro deck as your main character would get frozen. Waiting and using X-Factor Plot Twist to get two experience in one turn could prove useful to minimize that time but that may end up being more of a midrange deck.
For the turn(s) Winter Soldier is frozen I feel like the objective of stunning the MC every turn which is what aggro decks want may be a little harder than usual so perhaps a midrange strategy is the way to go. I love the card thematically and I'm excited to see what the rest of this set brings.
Here is the official Spoiler: http://upperdeckblog.com/2015/12/twas-the-night-before-vs-system-2pcg-winter-soldier-defenders-preview/
PauperTim is this websites owner and has always been into games of all sorts. He is a founder of the Pauper format for Magic: The Gathering. You can find him on facebook, twitter or OCTGN as PauperTim or as TheOrangeMitten on Magic Online.