how was it received?
It was highly praised by critics
Angel of Death (Slayer song)
it was highly praised by critics 
who is the song angel of death about Nazi physician Josef Mengele's human experiments at the Auschwitz concentration camp during World War II. by whom was it composed? Jeff Hanneman
wiki:19484871
Angel of Death (Slayer song) [SEP] Reception
Although "Angel of Death" did not chart, it was highly praised by critics reviewing "Reign in Blood". Clay Jarvas of "Stylus Magazine" observed how the song "smokes the asses of any band playing fast and/or heavy today. Lyrically outlining the horrors to come, while musically laying the groundwork for the rest of the record: fast, lean and filthy." Adrien Begrand of "PopMatters" remarked that "There's no better song to kick things off than the masterful 'Angel of Death', one of the most monumental songs in metal history."