Epic orchestral music is composed with the classical orchestra in mind at all times. Even so, ultimately elements are merged and in the end it becomes epic hybrid music.
Orchestral instruments are mixed with modern musical instruments, the string section cannot be missing and is often combined with choral music.
Percussions that are not so common in the classical world can be used, such as taiko drums. Also synthesizers and arpeggiators can be used, the composer Hans Zimmer is a good example of this.
Sometimes electric instruments like the electric guitar and even the electric bass are used. Also the drums can be mixed.