metal creates alot of tension quickly then resolves for a longer period of time. Tension and resolution are pretty basic theory principles. Resolution is usally achived by going to the starting note of the song or the note it sounds like it should end on. Alot of metal bands that ive heard lately create a complex rhythm on the note of resolution. Also alot of metal is based off of classical music (not rock, i mean old school like 1500s)

The Thing that Should not Be is in drop D