@CountryMage
To keep up with the scale of production of an exponentially increasing workforce. IE with self replicating golems/ robots 1 bot becomes 2 bots, then 4, then 8, 16, 32, 64, 128, 256, 512, 1024, 2048, 4096, 8192, 16384, ect at a shockingly fast rate. You're quickly gonna snowball past the material resources that one dungeon can create on a timely basis. And if you want to build a Dyson swarm that can encompass a star the size of our sun you need a mass of raw materials on par with at least one entire planetary mass / you might actually need to dismantle multiple planetary bodies to amass sufficient material to create a fully encompassing Dyson swarm capable of capturing 100% of the star's energy output.
One dungeon nor even an entire planet's worth of dungeons is nowhere near enough resources needed to sustain a stellar engineering project. And if you're aiming to fight cosmic beings then yeah your gonna want to harness the power of completed stellar engineering projects.
Given that dungeons are a useful resource though I could see an advanced magi tech empire dismantling entire planets save for the dungeons which could be preserved as the cores of space stations dedicated to renewably farming that dungeon's resources. But yeah in order to fight beings capable of devouring entire worlds then you need to form an industrial complex that is similarly capable of devouring entire worlds.