Sabrina900 is the sister of MasterSkymning. She hadn't come to exactly help with the whole war, but just monitored and came to talk with some friends she made on CC. She wasn't a very active member on the HB Wiki, so she could often be found on Community Central Chat. Though she was often away, it was worth an effort to contact her.
She ended up becoming afraid of the war and said she was leaving Wikia totally. She saw what it was doing to her brother, too. Sabrina didn't want to end up like him and it was frightening enough according to her.
Though she has left, it is known she is safe and alive still. It's doubtful she would come back to Wikia at all, even under another username.