Originally posted by mk_thot:

Like, can I beat him in a different world and bring his trophy into my main world to prevent this? Or does hanging the trophy at the altar trigger the change as well?

Yes to the first question, no to the second.

Originally posted by mk_thot:

Like, can I beat him in a different world and bring his trophy into my main world to prevent this?

Yes, this is possible

It doesn't replace Greydwarves, they are still the most common in Meadows at night. In fact the Fulings only rarely spawn in groups of 3—and none of them will ever be starred.

So, rare spawns and Greydwarf/Skeletons are far more common. I don't mind it at all and when I do run across them I just consider it a nice delivery of 3 Black Metal to my main base.

As others said, it's possible. I wouldn't do it if I were you.

First off, the early invasion events are not very dangerous. Progression through the earlier biomes also typically doesn't take so long as to 1) let many invasions to occur in the first place and 2) let you build up such an infrastructure that would take too much time to rebuild in the event your base is successfully sieged by the "armies".

Secondly, the material delivery to your doorstep can be quite convenient, especially in case of fulings (scrap, gold, totems), but also surtlings (cores and coal are always good) or bats (if you don't have a base in meadows or a boar farm).

And finally, the nightly spawning enemies will also fight among each other. When fulings first enter meadows and forests, it can be pretty intimidating experience. Soon after, you'll be glad for the extra black metal scraps found around your base. Later on, when seekers join the fray, you will quite often find them fighting against the fulings. All the mistlands mobs are also much easier to discover by hearing in meadows since there's no mist to dampen their noise.