Heavy/metal guitar players i need advise?

hey im sooooo stoked man im 15 been self teaching myself since 12 and ive struck gold. i can finally play metallicas the day that never comes through and through solo and all. but now i dont know what to play. i ned a new awsome scale or something (not harmonic minor i cant really solo on it ) or a song that pushes my limits so help me out on this one