When I faced him all my characters were on lv. 60+, so I was pretty strong. If you have Millenia's paralyzing special attack that works extremely well on Varmar. And the stronger you are the longer the effects will last. Make sure to have plenty of recovery items and spells in case you can't keep him bottled up, he makes pretty good damage

if you're fighting him for the first time the above answer doesn't apply as millenia won't
have the eye's skill yet (and you'll be a ways off lv 60). make sure you're using skills,
especially life up, and don't forget to use items. I like to attack the smaller critters
first, and get the boss alone. If you've tried that and it's not working, try going all
out on the boss, and make sure one of your party heals you guys every turn

if you're fighting him for the first time the above answer doesn't apply as millenia won't
have the eye's skill yet (and you'll be a ways off lv 60). make sure you're using skills,
especially life up, and don't forget to use items. I like to attack the smaller critters
first, and get the boss alone. If you've tried that and it's not working, try going all
out on the boss, and make sure one of your party heals you guys every turn but have one on
safety first

Always bring many healing items and mana potions it will help if one of ur people for
example Roan. And to defeat him u need to keep killing the Valmars Eye with a single
attack or a group. I made it when I was lvl 29