Originally posted by Mr Master
Galactus at full power,
would be far more powerful than the Alternate Galactus from the Black Celestial arc.
An yet that Alternate Galactus absorbed the Black Celestial (most powerful Celestial)
That Alternate Galactus was absorbing the Alternate Universe he was located in.
That Alternate Galactus (according to Reed)
would have not been satiated even after absorbing all the History (Timelines)
connected to that Alternate Universe,
(which equals to tiny UniverseS, as many as old as that Alternate Universe was)
This means Galactus was gojng to keep absorbing into the Multiverse.
In Marvel,
every Whole Universe has a Tiny Universe connected to it,
for every second in time in the history of its existence. (Past-Present & Future)
Most of these "Tiny UniverseS" (Timelines)
must be awaken (given birth) by travelling to said point in time.
As amazing as this Alternate Galactus was,
he is nothing in comparison with 616 Galactus.
616 Galactus, became one (merged) with the Previous Universe (Infinity Being)
and was created as an equal to the Totality of Eternity (Multiverse)
in the New Reality Marvel Universe (current Marvel Universe)
that was created by the IB.
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The greatest feat performed by a Phoenix incarnation was in a What If comic,
where an Alternate Jean Grey (Phoenix)
consumed the Alternate Universe she was located in.
Unfortunate Jean was consumed aswell, (died)
The infamous "Jean holding a universe in her hands" in (Here comes Tomorrow)
was always mistakingly interpreted.
That was a 616 Timeline (Reality 15104 - a Tiny Universe located 150 years in the Future)
Actually it wasn't even that,
it was a "possibly Alternate Future" of Reality 15104,
Reality 15104 - which was the Timeline,
(150 years from the Present) connected to 616.
This is why the Phoenix Force consciousness clearly states,
"it's a badly wounded Orphan Universe,
it Lost its Parents when unity broke out across the Megasystems"
This is because ALL Timelines connected to 616 or any other Whole Universe,
are the "babies" if you will, of the Parent Reality (or Whole Universe)
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Bottomline:
Phoenix is essential to the Universe, it is a Universal force.
Galactus is essential to the Universe, he is also a Universal force.
The difference?
If Phoenix dies, only the living beings that need the Stars to survive would die.
Any self-sufficient entities or beings would survive.
(Many cats sustain their own UniverseS without any need of the Phoenix Force)
If Galactus dies, all of Time & Space across the Multiverse folds/dies (Abraxas)
And if all of Time & Space in the Prime Multiverse dies,
then the entire Omniverse dies too, in a chain reaction,
because the 616 Universe is the foundation of the Omniverse.
This makes Galactus far more important than the Phoenix Force.
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Phoenix has never performed a Multiversal feat under its own power.
Neither has Galactus, but atleast we have proof that Galactus could have.
So IMO,
the hypothetical Full Powered Galactus would win.
Well written post. And yes G at full power would be awesome, but I'm afraid we'll never see him like that

. But at full power G should win.