Terrible things lay below Ooo. Older than the kingdoms, older than Marceline, older than the Lich. Older than the world itself. The Fire Kingdom has dug too deep, and now nameless machines of death have brought it down, and only the Flame Princess is left to tell the horrors, that the Necrons hae come to Ooo.

When the hunt for a rogue mage results in Sergeant Titus's squad being transported to the land of Ooo, they meet new heroes and face an evil unlike anything they've ever seen. Contains FinnxMarceline, don't judge if my Space Marines aren't perfect.