OverSoul

Oversoul is a free online PVP turn-based combat Battle Card MMO game that plays right inside your browser! Collect cards by battling over 190 monsters and other players in turn-based combat. Cut the deck and hit’em hard in high-score leaderboard tournaments... because the most important game to play when your luck runs high is the one where you possess all the cards!

You've just been slain by a horde of demons led by Nulgath. They are destroying towns and taking the souls of the people for some dark purpose but your soul escapes capture. You hear that there are 7 Crystal artifacts, imbued by ancient magic, that may hold the information you desire to restore your body and soul to their original condition. But no one knows where they are of course. So your search begins. You soon discover you have the ability to possess other physical beings be it creatures as great as dragons or small as a pixie. You use this ability to help yourself on your quest for the ancient artifacts.