Well... I'm not sure that's gonna count. The problem is, there are loopholes in which, other characters could now be considered contenders as "multiversal" dealing with that logic. It's kind of like Eternity and Infinity. They both operate within their specific universe, and... according to the evidence presented, the Phoenix being an abstract entity, would also operate within its particular universe, not that it can't necessarily travel to other dimensions. But it does belong to a particular universe, servicing that realm with life, psionics, etc, etc.
Good question, I asked that, and what was presented to me, was that there's only one version of a multiversal entity, as they do not exist in any one universe, but outside of them, existing within the realm containing all universes. This is where Multi-Eternity was brought up, as Multi-Eternity IS multiversal, where as universal versions of him as "Eternity" exists per universe. A "Multi-Phoenix" has never been established, and even as WPOC, she only affected a potential reality/universe, which is not considered a "multiversal" feat. Multiversal, is Magus using an INCOMPLETE Infinity Gauntlet to merge two universes together. This instance was used to explain why Infinity Gems are indeed multiversal in power, but it would require beings of exceptional power themselves, to realize the Infinity Gems' full potential. Thus, the Infinity Gems used by Thanos and others, can only manipulate their respective universe.
That could be stated, but... to some, I know how these people think, they would say that's a weak argument. The Phoenix Consciousness is unitary, and connects with all Phoenixes of other universes... but it becomes hairy as other entities become contenders now of being considered multiversal. Great examples used were Gambit as the New Sun, and Havok, in becoming the Nexus of Realities. New Sun literally traversed the multiverse/multiple universes, and affected them, and Havok became the Nexus of ALL Realities, using his powers. Magus is also mentioned, as he took an INCOMPLETE Infinity Gauntlet (which is why many consider the Infinity Gems greater than the Abstract Entities, and multiversal in power) to merge two universes together. These are some of the most multiversal feats discussed, and yet, none of these characters are considered "multiversal". Multiversal is being defined as a singular entity, with abilities affecting more than one universe. The Phoenix has yet to shown that, as I've seen presented...
There are multiversal feats mentioned of the Infinity Gems. The primary one being Magus wielding an incomplete, Infinity Gauntlet to merge two universes together. Also, they were remnants of the very first cosmos so. It was explained by some that the Infinity Gems can only affect according to their wielder. Thanos only has the power to affect his own universe, whereas Magus, a more powerful entity, had the power to use only a few of the stones, to affect more than one universe. The Phoenix has yet shown affect of more than one universe, as far as I've been shown. And even what I've researched... I've not seen a solid multiversal feat of the Phoenix.
Um... okay ^_^
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I'm playing devil's advocate, to really bring out if there's an irrefutable instance of the Phoenix having a multiversal feat, and being multiversal in totality. I... want these new writers to have a full, true perspective of what the Phoenix is, before... reconstructing it (as I'm seeing them do...)