So MC is a head that has tentacles and can posses other people, but was a biologist in his past life, and new world it is apocolypse with monsters but they're weak to copper so copper walls around cities, china still exists as dragon country or something but MC ain't in china. Kinda steampunk age, but there also systemish thing that sends you to different worlds, and they very hard. MC also has own labatory+prison/home thing in head, and can graft other stronger bodies onto his host, making him stronger. Spoiler: Spoiler about world and what he gets He goes to the world of IT but weirder and the clown is stronger, and he takes the arm and later body of clown to use it and get stronger.