If you are talking Jean with the Phoenix Force snapping (I.E., Dark Phoenix), She could take everyone up to around Spectre, and the catch there would be whether The Presence/Yahweh (whoever their God is) is either alive (he got capped by his Angel of Death) or empowering Spectre to stop her. If Yahweh/Presence is not around or not empowering Spectre, the next line of defense would probably be Michael. I don't see her getting past him. He might bring her back to her senses since Phoenix is beyond death.
If just Jean with the codename Phoenix, probably get up to Flash or maybe Supes, a skilled GL like Kyle or John could stop her, Wonder Woman, etc., any character on that level but just below Manhunter (who in my opinion is above Supes).
Is Zatanna really that powerful, or is this more of that "Say it backwards and poof" power she has? I can understand Dr. Fate (Lord of Order and all that), but Zatanna? She's not even the strongest magic wielder on Earth, Tim Hunter is. Plus, she'd have think of a spell to say, then say it backwards to attack Phoenix even using that ability. Having to think against Phoenix is not a good thing, that takes to long. She'd be mind wiped to quickly facing Dark Phoenix.
he doesn't choose his power.
Then again i can't tell how powerful he was since i didn't read that comic.
but do you understand what iam saying.
You can't use him as a good example.
At one time the spectre couldn't do shit to some common criminals.
his like Gods slave. Can be unbeatable and at time a dummy.