Future expansions.

But phoenixes don't suit elves in any way.

So, I just can't understand it.

Then chimeras can be made champions of Sylvan.

Added 10 minutes later

Especially considering vampires and liches.

By the way, not quite. Vampires and liches steal life energy. And phoenixes do everything on their own, which is closer to regeneration from the Earth magic school than to the methods of necromancers.