The Phalanx are part of the Technarchy, which is a living techno-organic collective capable of absorbing both energy and even the mass of living beings. The Phalanx are a very hostile safeguard that makes sure the techno-organic virus does not become contaminated by what it consumes, and while this isn’t inherently evil, the Phalanx sometimes see certain types of life as contamination.
The Phalanx also have the ability to assimilate others. In the past they have assimilated many powerful cosmic figures such as Drax, Gamora, Nova and the Spaceknights. One of the most notable appearances of The Phalanx was in Annihilation: Conquest and involved them being taken over and used by Ultron - this would be a great way for the MCU to have another run at the deranged AI.
Marvel could bring Annihilation: Conquest to life using the Ultron-Phalanx to turn friends against one another. Not only would it help introduce the Phalanx, but it would establish Ultron as a constant looming threat, much like his existence in the comics. Ultron always finds a way to survive. It could be that he was hidden in the computer of the Quinjet that Hulk took into space before the events of Ragnarok. From there he could have encountered the Technarchy and turned his motives to cleansing the galaxy rather than cleansing just Earth.
Gary has been reading Marvel Comics since he was 6 years old. Rather than retain knowledge on things such as Maths or Science - he chose to become a sponge for most things Marvel. He has a longstanding grudge against Iron Man he has harbored since Civil War(2006).