Magic introduced at the end of the 6th biome is way too late for a whole new system that can dramatically change your playstyle. I have put a lot of thought into a magic system that eases you into magic without taking away from the Mistlands.
Keep it simple. Useful, but not powerful enough to be a main playstyle. Save the refinery for later. Mistlands should still be the "magic biome" but not come as a surprise
Each boss until the Queen now drops Raw/Unrefined/Crude Eitr. The description could say something like "the magical essence of a powerful being, trapped in a gooey ectoplasm" or something similar. This is the main ingredient for a handful of magic items. 1 per biome. Also a couple new Eitr foods using yellow mushrooms, to give it a use. Maybe 1-2 Eitr armor sets
Meadows: Healing Rune (3m cd): drops a healing zone that heals players over time
Black Forest: Fire Wand (2s cd): shoots fireballs
Swamp: Poison Staff (2m cd): drops a poison cloud
Mountains: Ice Staff (no cd): channels a cone of ice
Plains: Meteor Strike/Magic Shield (3m dc): summon a powerful meteor or summon a shield
These are just suggestions. Let me know your thoughts!
Source: https://www.reddit.com/r/valheim/comments/12cshnj/simple_early_game_magic/
