Noisecreep has issued their list of the greatest guitar duos in metal. Along with essential (if predictable) pairings like Dave Murray / Adrian Smith of Iron Maiden and Glenn Tipton / K.K. Downing of Judas Priest, they include some excellent outliers like Hank Shermann / Michael Denner of Mercyful Fate:
(They) unpredictably darted in an out of King Diamond’s vocal lines, answering his strange aura and giving as much “voice” to the songs as King (which is really saying something).
And Jim Matheos / Frank Aresti of Fates Warning:
Matheos applies more traditional methods to his lead playing, always coming up with the right notes and having that signature but it was Aresti that possessed a particular fire and an ability to pluck unorthodox note patterns from the ether and make them work.
Listen to and read about several other bands without “Fate” in their names at Noisecreep.