Well... as long as you don't destroy another card you can keep on "going back in time" bringing the same card back. (basically creating a paradox
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) That's one of the reasons why this is a spell instead of a permanent.
Btw, if you want me to be a little more specific, I explained something similar on the first page.
Now, about the phoenix:
Good question, I hadn't think about that. I guess that at this point is up to Zanz to decide what to do with that special case. (But he has to like the card first
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) Anyways, taking the fact that the only difference with the phoenix is that it can be reborn, I think there's not really a reason for the card to work different. Remember that the ash is turned into a new phoenix, a new life... technically the old phoenix died.
Never mind my opinion, what do you think?