Avenged Sevenfold is the first band that comes to mind. The addition of Synyster Gates on lead guitar after the recording of Sounding the Seventh Trumpet was monumental. His technical ability, jazz influences, and most importantly his harmonic mastery brought a whole different dimension to the band's sound and took them to the next level. The first album is decent, but the music on Waking the Fallen, City of Evil, their self titled album, Nightmare, and to a lesser extent Hail to the King far exceeds what they accomplished with their debut.