Qasr Bint met Jebel Rum and Tel Hesani just as they were about to be sentenced to death and adopted them into the Um Biyara with the intention of travelling to Tabaygat to gain invincibility and great strength. His followers were all required to cause themselves pain and Qasr Bint claimed that they had to torture themselves in order to redeem themselves of their "sins". He and his followers brutally slaughtered the members of the Um Hamata because they thought they were evil. However they were later attacked by bats belonging to the Um Gathaah and Jebel and Tel Hesani managed to escape. Bint later caught up with them along with five of his followers when they arrived at Tabaygat and attempted to request invincibility from Sabbah Eid (though he didn't believe in Sabbah Eid). Sabbah Eid quickly incinerated him and the remaining Um Biyara.
Qasr Bint was an evil, sadistic maniac. He claimed to be on a mission to cleanse the world of evil but in reality he took pleasure in watching other people suffer. Qasr Bint believed that everyone had to cause themselves pain in order to ensure they would reach the afterlife. However he never harmed himself, showing that he was a hypocrite as well as a sadist. Qasr Bint refused to believe in any religion other than his own and was under the delusion that he was doing the right thing, which shows the extent of his insanity. He called his followers his sons and daughters but didn't care about any of them. Qasr Bint was also a cannibal, eating the flesh of two of his own followers and members of the Um Hamata whom he and his followers murdered without any mercy or regret.