Originally posted by whirlysplat
But is she really all that?
Answers please people
Well actually as well as being stated to be responsible for making the multiverse(a feat alone which places her well above the likes of Galactus) in F4 and Xmen The End. Phoenix contained the power of the multiversal reset switch that is the M'kraan crystal. A feat that Gambit and the X-ternals #3 stated was beyond all but Phoenix. Xmen Forever also showed that the power of Phoenix is something all humanity would eventually attain. It is the ultimate mutation as stated in the comic, a state which when reached by humanity places them above the abstracts and the Living tribunal who all get replaced. It is the end of all that is in the natural scheme of things. Eternity in that series talked of the importance of Phoenix and declared it the resurrection force the "assurance of life after death". The force that creayes everything, is one with everything and eventually destroys everything before beginning the process anew.
Phoenix has fought Galactus on 2 occassions and came out the better in both encounters.
The first occassion was in a what if called What If Phoenix rose again. In it instead of killing herself Jean Grey allowed the Shi'ar to perform a psychic lobotomy on herself removing all parts of her brain which were responsible for her psionic powers. Jean Grey fought against Galactus after the Shi'ar asked for the Xmens aid in defeating the planet eater. Jean Grey had up to that point been powerless after the surgery but as Cyclops was about to be killed by Terrax, her phoenix power emerged again. She quickly dispatched Terrax and then went on to fight Galactus and she stated that because of the lobotomy her powers were at that point relatively limited to the point where she wasnt sure if she could beat Galactus, however she said that her powers increased along a geometric curve every time she used them. Galactus and Phoenix fought and Phoenix got the better of him. While his efforts were shrugged off Phoenix caused him pain. He then tried to forge an alliance with Phoenix claiming them to be equals. Bear in mind that this was a limited Phoenix yet in this state her power equalled Galactus at that point. She went on to destroy his machinery and Galactus left the planet for an easier meal claiming that he couldnt be bothered with the effort and that had he stayed he could eventually dispatch Phoenix. A limited Phoenix versus a hungry Galactus and Phoenix clearly got the better of him and caused him to abandon his meal. Phoenix went on to continue using her power in missions and as she said it increased to its previous levels. She went on to revert to Dark Phoenix and after killing the Xmen went on to destroy the universe "destroying everything in her path". At that point Galactus obviously became a non factor.
In their second encounter which occurred in Excalibur #61 Phoenix fought Galactus again because he was about to consume a planet. The two fought and while Galactus' blasts had no effect Phoenixes blasts hit home and Galactus was leaking energy from his armour Phoenix was fine and Galactus talked his way out of the fight by telling Phoenix that she's just as bad as him if not worse because he may eat planets but she draws energy from future generations "life yet born":
"""Here i lie exhausted from our struggle while you are neither weary nor hungry because you tap into a source of near limitless potential. The sea of life yet born""
Galactus may not have been at full power during this encounter but even so his efforts had no effect on phoenix and what you must remember is that even if he was Galactus' energy source is finite while he burns up his energies and would eventually tire and run out of power, Phoenix could keep on going and be just fine at the end of it as shown by Galactus' comments here. If the battle continued it is fair to assume that Galactus would have been destroyed.
So Phoenix has defeated Firelord, Nova and Terrax, is shown in Xmen Forever to be greater in power than even The Living Tribunal, contained the multiversal power of the M'kraan crystal, joint the universes of the multiverse together by projecting a doorway through the multiverse(As shown in Excalibur) is stated to be the beginning and end of the multiverse and has held the 616 universe in her hand and telekinetically restructured it after having amputated an undesirable future. Phoenix hasnt fought a lot of people but her feats place her at the top end of the hierarchy.
For any extra information check out Classic Xmen 8, 24, and 43,
Gambit and the Xternals 3, Uncanny Xmen 101 -137, Xmen Forever 1 to 6, New Xmen 128, 151 to 154 and Phoenix Endsong.