He had torn off the assassin's mask revealing a lipless mouth cut wide across the man's cheeks filled with razor sharp teeth.
Underneath his mask, the assassin was wearing purple gloss on his lips. 
mnli hypothesis: Underneath his mask, the assassin was wearing purple gloss on his lips.  premise: He had torn off the assassin's mask revealing a lipless mouth cut wide across the man's cheeks filled with razor sharp teeth.