Originally posted by Accel Lex:

I haven't been invaded in a long time. The first time since I stopped playing was tough because it caught me by surprise and I was running around small base. Second time was easy since I just focused fire on closest rather than running around seeing what's happening. Last time easiest since I had better gear and just shot the trolls.

I looked up and saw that the more bosses you kill, the more enemies spawn. So I wanted to see good defenses to weed out the weak so I can focus on the bigger threats or manage the threats.
I saw that in historic warfare, a ditch and palisade were an amazing defense considering how effective they were relative to the cost.
In this game, I heard enemies don't attack up or down (can't remember which) often if at all so it'd be a good obstacle for most enemies. The bigger trolls would be less effective, and I heard bats exist that will mess with livestock.

Most mobs in the game are vertically challenged but not all. This is why high earth walls and trenches are effective methods of dealing with many.

Each time you kill a boss -on the same map seed-, you progress in the types of events that you can encounter randomly. Eventually there are two events that involve flying creatures and those will not be able to be turned away by high walls or trenches and bats, as you mention, is one of them(stir the cauldron). The bats are bad for tames but not much else in fear of structural damage etc to a base really. However the drakes you'll also need to be mindful of.

https://valheim.fandom.com/wiki/Events

All other events though(so far) can be countered with the high earth walls or trenches. You just need to also make sure that you have something like workbenches carefully spaced in and around your base to also prevent any other sorts of random spawns from happening in your base not event related.


There are also 2 other alternative ways to avoid most/many events.


1. The multiple map seed method-- Having your main base on 1 map(where you hand the trophies of bosses for example BUT not killing any bosses on that map, and then having separate maps for -each- boss kill means that you'll never encounter any event other than the boar/neck event. This means you can make bases a little easier though the biome location for your base may require you to build still wall/trenches too mind you.

Think on each map seed as a "portal" world if you will. This method also allows you the ability to go around the restrictions with transporting metal ore/ingots.

2. Build your main base on a small island very very far from any other land mass. The events have a radius and spawning in/over the ocean(again has to be far) can prevent many events. Downside is finding such a small island to build on and the issues of transporting things to and from the island.