I'm just looking for a card to change text from "player" to "opponent" in {mist of stagnation}
I'm afraid no such card exists. The only cards that change text of other cards can only change;
1) color words (blue, red, etc)
2) basic land types (island, mountain, etc)
Or in one case
3) creature type (wolf, human, angel, etc)
Heck that would be even worse because whoever controlled the mists would never untap anything.
{rest in peace} combo waiting to be abused lol
If you want to make that card one-sided, use {Tormod's Crypt} and such to limit your opponent's grave.
Vigilance creatures+{blustersquall} etc ftw?
I just used {Thoughtweft Gambit}
I love the card name more than anything