Originally posted by Shurenai:

Originally posted by wizard_of_woz:

Just know with enough terrain edits your world will start to lag real quick.

This isn't as much of a concern as it used to be, not even close to it. Used to be that every swing of your hoe was an additional instance the game had to keep track of- So a extensively modified area could end up with 10-30k+ instances and dramatically hinder performance when in that area of the world.

Now it just keeps the most recently applied one Even after moderately extensive terrain modification my area has around 4-5k~ instances. The untouched and unmodified meadows forest I travelled to has over 7500. So.. Don't stress too much about extensive terrain modification anymore :)


To the OP, Check out PlanBuild. It's building tool is pretty awesome and one of it's functions is a terrain modification tool you can use to flattten wide areas to a specific height. Plus you can plan out your build using the planning function, make blueprints, have your plan auto-built by the builder machine (requiring resources) or just build directly (no resource cost), etc. I've been using it fine for a couple weeks now.
https://www.nexusmods.com/valheim/mods/1125

If you want something more vanilla, you could check out the HoeRadius mod, lets you increase or decrease the area of your hoe or cultivator's effect- Letting you hit small or massive targets. Even if it' not quite the flattening tool you want, I'd still recommend it for being able to shrink the area to be able to style your area more specifically, like putting patches of grass on a dirt road or whatever.
https://www.nexusmods.com/valheim/mods/1199

And the already mentioned SkToolbox also has some terrain leveling functions.
https://www.nexusmods.com/valheim/mods/8