Synopsis
The Phoenix Force returned to Earth to choose a new host. It took many heroes and villains into itself and caused them to fight 1-on-1 battles across the globe, expelling the losers. Now only 6 remain and they have been paired off in more contests, enhanced as usual by portions of the Force. Some of those expelled and some who weren't chosen have teamed up to fight the Bird Of Fire itself near Avengers Mountain HQ. And the 1M BC Lady Phoenix has manifested to tell Thor that *she* is his mother, not Gaea.
Black Panther and Captain America are duelling all over the dead Celestial body that is Avengers North Pole HQ. They are equally-matched, but Steve Rogers is fighting to find a way to stop the PF choosing *any* host while T'Challa regretfully accepts that the Phoenix will choose *someone* and that he himself is the safest choice. He reminds Cap of the cave painting they found (#1) and how Iron Man went back to 1 million BC and met (#28) the proto-Avengers (Lady Phoenix, Odin, Agamotto, a Black Panther, a Ghost Rider, an Iron Fist and a Starbrand). Now the Avengers once more include Thor, a Black Panther, a Ghost Rider and the new baby Starbrand, and as allies an Iron Fist and Dr Strange as the Sorcerer Supreme successor of Agamotto. BP believes that they also need a Phoenix to survive the Age Of Chaos (that Mephisto has been brewing throughout this series). Cap is more worried that a Phoenix will add to the Chaos.
Shanna the She-Devil (with Zabu the sabre-tooth tiger) is battling the Russian Red Widow in New York harbour. Zabu gets slammed into a ferry, taking him out of the fight. Shanna carries the ferry to safety even though it allows the Widow to strike her. RW claims that her life of training in the Red Room has (literally) scarred her but readied her to become an assassin of worlds, but Shanna is too pretty to have been through something similar. But the She-Devil responds by demonstrating her savagery.
The 3rd duel is between She-Hulk and Sub-Mariner over Moscow's Red Square. The Winter Guard (in this case Crimson Dynamo, Darkstar and Vostok) have been called in but can only watch, and note that the combatants exhibit the same energy signature as when Red Widow 'disappeared'. She-Hulk doesn't care about becoming the Phoenix herself, she's just determined to stop Namor winning the prize. Subby on the other hand is determined to win to save his Atlantean people from the depredations of the surface world. (He happens to mention that he's already killed Echo beneath the waves in this contest.) The Phoenix power has made Shulk more savage than ever and she rips Namor's arms off. But SM had the power once before (during the Avengers Vs X-Men event) and he knows how to wield it as he remotely controls his hands to strangle his foe, and then rejoins the arms to his body. She-Hulk crashes to the ground.
Back in Avengers HQ ex-contestant Moon Girl is monitoring these happenings and reports that the Phoenix itself is escalating in power. Captain Marvel and Ghost Rider keep the Bird chained in place as Iron Man prepares to shoot at it with the dead Celestial synced to fire as well. Thor wants to help his mother but another ex-contestant Valkyrie is holding him back with the All-Weapon in the form of a chain.
Shanna and Red Widow are still fighting in the harbour. Shanna has shattered RW's mask, revealing the multiply-scarred face within (Dr Doom, eat your heart out). But we start seeing a voiceover reporting 'death' followed by an internal fire and wings, as a hand reaches out from the water. The winged being of light takes the fragments of Phoenix Force from Widow and She-Devil. Then it moves on to Moscow, musing that the Phoenix was never looking for a winner, but for someone who had fallen. Then it takes the Force from She-Hulk and Sub-Mariner, but this last 1 not without a fight. As they duel the being realises that the Phoenix was drawn to emotion, and in this case to someone who can utilise any weapon and fighting style. (And Namor recognises Atlantean Kraken-style martial arts being used against him.) Almost as an afterthought Cap and Panther lose their Phoenix power.
At Avengers Mountain Thor approaches the Phoenix. (If Iron Man fired it doesn't seem to have made any difference.) Lady Phoenix appears before him again to say goodbye before she rejoins the Force. The voiceover continues and says that her people the Cheyenne have a legend of a bird of fire the Thunderbird. We now see that the 'winner' is Maya Lopez/Echo (and Thunderbird will apparently now be her superhero codename), and her Phoenix power manifests in wings and in lots of little firebirds.
In the Summer House on the Moon Marvel Girl/Jean Grey mentally contacts Logan to tell him to stop opposing the birth of the new Phoenix. She reaches out to Maya and offers her help. As we see Jennifer Walters in the ruins of Red Square, Sub-Mariner spurned by his Defenders Of The Deep, Thor venting his rage as a storm, and some of Echo's little birds visiting baby Starbrand.