A player with at least one character of Hero level 30 or higher may petition a character of Hero level to become an angel. The step from hero to angel is a serious one. It involves giving up your mortal equipment (do NOT donate or give away your equipment as an angel candidate), and giving up actually playing the game as that hero, in order to help your fellow players in the unique role of an angel. Read Angel for a basic outline of the class.
Those interested only in becoming an Immortal should not petition for Angel. Angel is completely separate from Acolyte, and is not a path to power.