Pentyn is a very old knight found in Enakhra's Temple.
Apparently, he and a few other knights of Avarrocka were sent to slay Enakhra and "burn her temple along with her."
Enakhra killed the knights with ease and then cast a spell on Pentyn to use him to bind Akthanakos (Pentyn's body being used for the blood sphere on the pedestal to which Akthanakos was bound) to immortalise him and keep him imprisoned in the temple. He claims to be very hungry and speaks about being tormented by Enakhra during his imprisonment.
The spell looks a bit like Ice Barrage, leading some people to believe that he is merely frozen with a Ancient Magicks spell that is a higher level than humans can manage. This is an example of the spell that Mahjarrat have been rumoured to be able to cast that prevents a person from aging but makes them completely immobile.