There Are At Least 2 Bands Called Mastery 1. A Canadian Thrash Metal Band 2. An American Black Metal Band 1. Formed In 2001 Mastery Canada Is An Old School Thrash Metal Band From Toronto Canada. They Could Not Find A Good Vocalist So They Decided To Play Instrumental On Their Debut EP Lethal Legacy Released In 2005. In November 2009 The Band Announced That Vocalist Billy Milano S.O.D. M.O.D. Had Joined The Band. Current Line-Up Billy Milano - Vocals Markus Armellini - Guitar Morgan Rider - Bass Kerry Saxena - Drums Former/past Members Maxell Black - Vocals Penetrator Krakatoa Kevan Roy - Drums CayM Jeff Dormer - Guitar Anthony Ristovski - Bass 2. Mastery Is A One Man Black Metal Project From San Francisco CA Formed In 2005