Originally posted by Gnome d'War:

I don't believe the troll theory. I've killed dozens of trolls on one world and never gotten a Ground Is Shaking raid there.

I think the Elder has to have been killed on the same world, iirc. I could be wrong though.

Originally posted by Soulstinger:

I believe the troll raid requires eikthyr to be dead AND a troll spotted in order to trigger

I've killed Eikthyr and then dozens of trolls yet there have been no troll raids.

The Elder must first be killed, and the player must have killed at least one troll. For me "The Ground is Shaking" occurred within moments of returning to our base after defeating The Elder.

I believe the troll raid requires eikthyr to be dead AND a troll spotted in order to trigger

I occupy a world in which no bosses are dead, and I have killed hundreds of trolls. "The Ground is Shaking" invasion event has never occurred, only "Eikthyr rallies the creatures of the forest."

I don't believe the troll theory. I've killed dozens of trolls on one world and never gotten a Ground Is Shaking raid there.

pretty sure that hanging boss trophies from the various biomes WILL cause the basic mobs from that biome to start appearing in any lower level biomes. So for example hanging Yagluth's trophy will make Fulings start appearing in the meadows biome.

its highly likely that it doesnt care about the world from which you got the trophy and only about wether you hang it up as the first option would introduce some problems.

There are some non-trophy based events though, like needing to kill a troll for the ground to shake. There may be some weird edge cases.

From testing I've done, the only thing that affects base attack event progression is killing the bosses IN THAT WORLD. If you live in a world in which you haven't killed any bosses, but you've brought the boss trophies over from some other world to mount on the shrine, you can have access to all the boss powers, but will only ever get "Eikthyr rallies the creatures of the forest."

Haven't been bothered to go to a new world just to kill Moder or Yagluth, but that would be an interesting test.