Hmm.
In theory a plague should save our Bone Wall 3 charges per Phoenix; 2 when the Phoenix dies and 1 when it doesn't attack for a turn. It also costs Fire one quanta to revive the Phoenix. So, if our Plague can knock out 2 Phoenixes it is worth it; if not, it isn't.
The main question is this:
How many Phoenixes will Napalm play? If she chooses 4-6, the Plague will be worth it, but if she chooses 1-3, it probably isn't worth it.
But I think Fire will only choose a couple Phoenixes, if any. They don't seem statistically strong in this matchup.
Immo is out of the picture; we have Bone Walls. CC resistance isn't necessary; we're out of heavy CC. This means Golems and Dragons mostly outclass Phoenix, and Napalm can fill the rest of the deck with CC.