As for where that power comes from? It's simple, Like every brain-dead novel like this it comes either from a space asteroid or some very powerful being put there.
its really good its just that the mc accepts just about anyone into his camp but overall its better than other mcs that have a walnut for a brain and he actually uses his minions well
this is everything i have been looking for a mc with a brain,dungeon building,smut,and something like necromancy(btw if anyone has anything similar to this pls rec)