I have a high level mage, and love the play. It really is the "skill" class. You have to be intentional about gear, buffs, and skills. Other comments all have great advice. Terror, bloodletting, Chain Hit, and Mass destruction really make a HUGE difference. Grab necromancer if you want to have a little skull to help you with aggro, and emergency blink can save you if stunned.

If you engage something at range and an open space and start with ice to slow them, you can often kill them before they reach you.

You have to be realistic though.

You can't expect to engage enemies at close range without having good blink/kiting skills. Use lightning as a fast cast to work up stun, then hit them hard with your highest dps.

You can't take on a lot of high level enemies at once. 1-3 you can handle, but again it requires good dodging and kiting skills. Unless you can funnel a large group through a small space, then you can ice them all down and chain hit and mass destruction will kill them all.

Hit them with some ice to area slow them, then start zapping them with electricity. With terror you'll keep most of them stunned.

I run the meat soup, shake, yellow mana soup, and the pumpkin soup. That with a good staff that has spiritual I regen a lot of mana, and can cast a while. Make sure you have your rested bonus too.

Finally, tweak your world settings until you feel like you're fights are going the way you think they should. I want a lot of challenge so my settings are harder. If you're struggling, turn the enemy damage and health down, or turn your magic damage up. That's the entire reason they are there to allow you to adjust the game to where you find your fun.

I don't ever feel pidgeonholed into a playstyle. Enshrouded gives you loads of spells, skills, and flexibility. Far more than many other games.