First off, how do you plan of killing the pheonix again and again?
Well, the revival is not guaranteed, and cost wise, it is not all that different from 1
to turn a 4 attack graboid into a 10 attack shrieker.
Plus this creature could be killed, ending the effect, of pheonix could be lobo'd.
Finally, that would require a
/
or
/
deck. Since those synergies don't really exist all that much right now, this combo would require a deck built exclusively around it for it to be effective, at which point, it gets beaten by things like lava golem or normal phoenix/immolation rush.
I am going to say that I do not at all think it is OP.
Furthermore, the upped pheonix generating un-upped pheonixes scenario would not effect most PVP, because usually upped cards are banned.
If upped cards are allowed, there would be much better decks.