Obtainable by trading Goblin Drinks to the "Scrawled Writing" in Oldton Movapolos, and killing the NM "Goblin Wolfman." It's a VERY low drop rate. I'm currently 0/12 (no TH).
(Edit: 1/2 with 60 THF husband in party, let him pop it, first attack, and kill it.) ^^
I didn't even mean to get this as a 54 PLD. A bunch of higher levels said they would help me get AF after a few runs. Stayed for a few hours to help a guy who was 0/29 before he got one >.<