Only the first cast is required to begin the process. After that, flux is considered a passive ability and occurs every turn. If it is killed in any form, it does not come back as another creature.
Basically, say you play this card. The next turn, you activate it with 1
. It then turns into some creature, say Vampire. After the Vampire attacks, it changes into another creature, say Chyssora. The poison ability is active, so you can use it that turn. It continues changing and repeating the process until it dies or the game is over.
I might change it to a pure entropy card, but I felt it was closest in effect to what fate egg does. I couldn't really decide whether to make this Time or Entropy, so I settled on both
*Parallel universe generates a copy of the current card with the passive flux, same stats (unlike mutation where it changes again).
*Effects like poison carry over. Freeze carries over but does not affect the ability to change.