Hi, new player here and i just wanted to get a bit of insight on these free-to-play characters available. I was wondering if the characters that are currently FTP are part of some kind of rotation that occurs every once and a while because i really enjoy playing Skye but i don't want to buy her right now if she totally free to play or if the duration of that status is far from wearing off, i'd like to better invest into buying the other characters that aren't FTP but if it means losing ,so...