Light Elf Mystics are projectile-based opponents. They're quite fast and like to hover around the battlefield, backing up their allies with magical attacks.
As with any foes that specialise in ranged combat, Mystics should be priority targets. Mystics are barely able to defend themselves once Kratos is up close, and will instead attempt to flit away from danger to a safer position. As such, it's best to kill these magic-wielders quickly once you're in their face.
Getting to them can be tricky, however. Mystics have three kinds of projectiles. The first is like a grenade, which explodes after a short amount of time, but it's easily dodged as long as you're paying attention. The second is a fast shot (usually followed by another fast shot) which can be blocked. The third, and most powerful, is a large ball of light, which will track Kratos at a slow speed. This one needs to be destroyed before it hits you, using your own ranged attack.
Mystics can be surprisingly troublesome foes, then, but be aggressive, watch for the ball of light, and you shouldn't have too many problems.
How many Light Elf Mystics have you smashed into submission? Be sure to check out our full God of War Ragnarok guide for information on how to beat every enemy, and much more.