Synopsis
Tony Stark has a dream in his bed in the Avengers Mountain HQ, the body of a long-dead Celestial at the North Pole. He dreams of the primitive Kree led by Morag slaughtering the plant-life Cotati in their garden on Earth's Moon, after the Kree lost a competition. When he wakes he remembers being shown that by Immortus, and the aftermath where the Kree also killed the Skrulls who organised the contest, sparking off the millennia of Kree/Skrull wars.
Captain Marvel (Carol Danvers) reports a telepathic SOS from the Blue Area of the Moon (coincidentally the site of the contest & garden) received by the remains of the Celestial's brain. The Avengers head there in a space-going quinjet. Tony remembers more details of the history. The Skrulls were an important mercantile civilisation at the time. They offered patronage to either the Kree or the Cotati, whoever made the most of an area of the Moon which they gave an artificial atmosphere. The Kree built a city and the Cotati created a garden. The Skrulls liked the garden better. And so it went. Later Uatu the Watcher made the so-called Blue Area his home, but it no longer had a garden.
But when they land they find the ruined city has now been overrun with vegetation like a jungle. However Captain America comments to She-Hulk that it's too quiet, there are no animal sounds. Suddenly they are attacked by a Kree Sentinel (a huge robot) with its head replaced by something with tentacles and teeth. It blasts Thor before he can throw his hammer. CM tries to absorb another blast but then they are all felled by a sonic attack. But then a green-skinned sword-wielder leaps to their aid and lops the head off. And the Avengers deal with the body.
The team greet the newcomer as an old friend. Ghost Rider (Robbie Reyes) asks Black Panther who he is. T'Challa tells him he is what remains of a great Avenger, Swordsman (Jacques DuQuesne) who trained Hawkeye in the use of weapons. He started as a villain but later joined the Avengers to try to redeem himself and died in the cause of Mantis, the Celestial Madonna. But later his body was 'reused' as a Cotati. The current 'Swordsman' describes it as a merger with an ancient Cotati intelligence, retaining DuQuesne's memories. And he adds that the Cotati have now re-greened what for them is sacred ground.
Robbie is still confused so Jacques explains how he and Mantis united to create a perfect Cotati/human hybrid the Celestial Messiah. Mantis left to explore the stars, but she has kept in touch. Thor recalls 1 such occasion (the Av: Celestial Quest limited series). Then the fully-grown Messiah (Sequoia/Quoi) approaches and announces that he is here to save the Universe from all evil. Thor asks Quoi what happened to his saurian pirate companion Raptra, but is told that their paths parted.
Quoi explains that this garden is the 1st step towards the Cotati paradise of universal peace for all life. But it could do with a little help, so he asks Thor to generate a storm to water it. Later while they share a vegetarian meal (so much for a paradise for *all* life) Stark reflects on the feeling of peace he's had since he got here.
Quoi also tells them that the robot they fought was a hybrid of Kree technology with a Skrull mutation. This is the sign of an alliance between the 2 ancient foes. The Kree have never stopped hating the Cotati. But now the Skrulls see choosing the plant-beings as their greatest mistake because it led to the long feud. And now they also have a figurehead to jointly rally behind (and we see the Kree/Skrull hybrid Hulkling). But he is really a pawn for the real powers behind the throne (and we see chars who I understand are Super-Skrull and Tanalth The Pursuer).
We learn that a joint fleet is nearly here to destroy the garden as a symbolic victory that will cement the alliance. Carol suggests alerting Alpha Flight for interstellar diplomacy (she's no longer in charge of that, but Abigail Brand is). Swordsman says there's no time for talk, they need Avengers action. Danvers reminds Stark how (in the Incoming 1-shot) they saw a Kree and a Skrull murdered with the message "beware the trees". Swordsman says murder isn't the Cotati way, but desperate times call for desperate measures. Iron Man stands up and gives a rousing speech calling them to arms. Cap and Panther agree to stop the immediate threat and *then* move to diplomacy. So Tony ends with "Avengers assemble".
But then we see that the approaching armada includes the Fantastic Four and their 2 children.
The issue says continued in Empyre #1, but I guess 1st we'll find out what the FF are doing there in Empyre: FF #0.