User blog comment:Pualover/Overlord Power Level/@comment-14.202.187.93-20150914030000/@comment-213.113.51.4-20150917214048

Also if I remember correctly a bit of a spoiler but in vol 9 Ainz states that he can "absorb"/"gain" xp from the enemies he kills in the big battle but that it would look extremly evil when he would do this so he refrains to do it. So as to not appear to evil or like a monster, it would literaly look like he would absorb their souls if I understood everything correctly. So it might even be possible to go beyond lvl 100.