I am looking for a manga I read a while back about a slime like creature, which can possess other dead beings, and gain their skills.

It's not Tensei Shitara Slime datta ken

I remember there is a wolf form, a boy form, and an archer girl form it can use, and it can lose the skills of those forms if it dies in those forms. I also remember there being a prison arc and an archer enemy girl

to your eternity

yes that's it, thanks!