Originally posted by qwerm:

Was there an announcement in yellow text when this started happening? Best I can think of really depends on where you are in the game progression. IF you have beaten Yagluth and this base that was attacked was in the mistlands, it's possible this could have been the "what's up Gjall" raid event, but again that only happens in the mistlands.

Could you elaborate on what else you saw, and/or are you running mods?

its a vanilla version, and that drop an item named "refined eitr"