Darkmount was a massive city-ship under the control of Blackout. When Blackout discovered that the Matoran Universe would soon become uninhabitable, he ordered every building to be disassembled and used the materials to build Darkmount.
It suddenly arrived in orbit of Bara Magna and destroyed seven Nathrezim ships within the opening barrage. Blackout later teleported to it, and left. It arrived again in orbit of Bara Magna soon after, where Blackout destroyed a group of Vrai soldiers and gave Ynot a subspace communicator. Malygos later teleported to it, and asked about the whereabouts of the Homunculi, the necromancers of Scholomance, and the Metru Nui Matoran. Blackout responded by saying that all the beings in the Matoran Universe now lived onboard Darkmount. Later, Darkmount appeared in orbit of Coridan VI, and began firing on its cities. After an hour, Darkmount warped to Earth, where it deployed legions upon legions of Rahkshi to destroy random targets. Then, it teleported a quantity of unstable hadrium into Earth's core, and warped away. Later, it destroyed Bara Magna, and warped to a planet that Malygos discovered and proposed to use as a base. Later, it escaped the planet, and dropped out of warp in orbit of Impel Down, thus beginning the first successful attack on a Shadow Proclamation-controlled planet since the war with the Vrai millennia ago.
Following that, Blackout merged Darkmount and Atlantis, creating a huge super city-ship, which was taken all the way to BZPower, where it was destroyed by Sasuken and Blade, only to be replaced with a copy of itself from a different universe about five minutes later. This new Darkmount was later cannibalized to form Blackout's new body when he absorbed Unicron's power, and was later destroyed by Kakamu's amplified Nova Blast.
The pieces of Darkmount were then ignored for a long time until some residual Unicron energy in one of the pieces caused the other pieces to fuse together, creating the Dark Mounted Crab, a giant robot crab made from Darkmount parts. The DMC then went to Shinobi-Nui, and attacked Blade. It was presumably destroyed.
- Darkmount is actually a copy of Atlantis built using specifications from the Order database.