Once In a Blue Moon Spoilers
The roles being auditioned for this episode are: Beta, Danny, Gamma, Marcus, Possessor Demon.
Source: Show Fax
Once in 50 years, an eerie blue moon lights the San Francisco sky and tonight is the night! A whitelighter named Danny is meditatingly leviating in the middle of an empty street. Leo orbs in to warn Danny he shouldn't be so careless and to also tell him not to approach the sisters tomorrow. The word is out about what Leo did to Zola (episode 7.01) and that no one knows on which side Leo is anymore, which is exactly why Danny will go see the sisters... it's a whitelighter's dream job! After Leo orbs out, we see a beast attacking Danny. It turns out that this beast is attacking whitelighters. Agent Brody tells Paige that a new threat is coming and that he can help but can he be trusted? The sisters try to find a way to take care of the beast. But what will they do when the beast they were after is... [them!] The Avatars are back and they are after the most powerful possessor demon in order to get help to continue what they've started... Leslie appears in the episode.
John Kretchmer directed the episode written by Erica Messer & Debra J. Fisher.
Source: Spoilerfix