Continuity mistake: Whenever Amon is on screen with his mask, the design of the mouth keeps changing: sometimes there are circles on the end of it, and sometimes there is a small angle pointing up. This can be spotted, for instance, when he is talking at The Revelation.
The Legend of Korra (2012)
Episode list - season 1
Starring: J.K. Simmons, Jeff Bennett, Dee Bradley Baker, Janet Varney
Answer: We do not see what happens. Avatar shows rarely have people killed on screen, so either he got away and was never seen again, or just died right there. As Amon was outed as a bender, he would not go back for his old boss.