There are several aspects of magic. The Fay and Zarth each exhibit them differently. This is an overview.
Tricking the senses. Creating fake images to see. False sounds. Even instilling feelings and swaying opinions.
Enchantment is based on creating arbitrary connections between things. In essense, this means bending and re-assigning causality. Instead of you using the broom to sweep the floor, the stream outside uses the broom to sweep the floor. Instead of the wind blowing through the leaves, the wind plays music on enchanted instruments.
The Zarth channel energy from various sources of sacrifice. i.e. Fatuge, time, life span, strength, or sanity. This sacrifice could be from coperate or individual means to corperate or individual ends.
Changing stuff into other kinds of stuff
Some kinds of magic can only be used by immortals.
Telling the Truth. Whether events occurring, occurred or to occur.
summoning and teleporting
restoring health, mending wounds, bestowing youth, granting years.