So at last, I finally killed the Summoner (but took WAAAAAAY too many hits, seriously gotta down that down). However, I died a few rooms later and when I went through the dungeon again, the Summoner returned ._.
I would suggest to not make him return so that I don't have to suffer through that hell hole again. It also feels inconsistent as to how there are some bosses that return and others that don't.
oh god I thought I made him to not to return I'm sorry...hehe time to write that down to change.