I have a couple of ideas that I think would be interesting in the upcoming Ashlands rework, so I'm going to share them here.
Rework of the terrain (obviously)
I think that the Ashlands could look very good if the ground was gray, made of ash and there would be ponds and rivers of lava, that could potentially serve as Surtling spawns. The air could also be grey and foggy, like ash blocking you from seeing far away, but not to the degree like in the Mistlands (image generated by AI to better explain what I mean will be in the comments).
A volcanic material, like basalt or something similar, stronger than black marble that would perhaps need explosives to be harvested. Said explosives would also be an Ashlands-tier item, as I think the place could have some sort of rare sulfur-like material, or something of the sort of gunpowder.
The volcanic rock material would be use to construct a special furnace that would be able to smelt flametal ore, which would be processed and crafted into equipment stronger than the Carapace set.
Necromancy could also be added, as magic powers do exist since the Mistlands update.
That's all I have for now. If you have any ideas that you would like to share, do so in the comments.
Thank you for reading this, by the way!
Source: https://www.reddit.com/r/valheim/comments/111eed9/things_i_think_would_be_interestingnice_in_the/