Okay so like how i start every card, it's true though, i like the card art and i think it fits the card every well. I like hove the dove is the symbol. So I think that this card needs a little work.
Upped card:
I like the basic concept of the card but I think that it may be too expensive or not be powerful enough. I think that the ability for it to just make one creature immune from it. It's basically like a weaker quint but in light form. So I think that to make this card more effective and be better looked at, it should say, "make all your creatures on your field and/or and future creatures immune to negative effects," or even say "make all your creatures on your field and/or and future immune and removed of negative effects.".
Un-upped card:
I basically think the same thing, making it so all your creatures lose the negative effects, you may want to also increase and decrease the cost depending on what you do to the future card.
Deck ideas:
I think that this could work against parasite/infection decks or even people who like to poison their voodoo dolls. I would like to hear what decks you think that deck would work in.
Well anyways, good luck!