In the game Oblivion it was told by Jauffre that Nirn was protected from the other planes. But after the crisis, this was restored again by shattering the Amulet of Kings, IIRC. So it should be safe from daedra in the game Skyrim.

Yet, I see Meridia as an Orb of light, Hircine as an ethereal deer, Boethiah entering dead bodies with ease, Molag Bal reviving the dead AND Herm Mora as a purple orb who has the power to make a person vanish(!) with ease. Oh I totally forgot. Mehrunes Dagon who still dares to permanent spawn dremora. (As if they left their plane by themselves through a gate. Remember that they didn't get their bodies banished after defeat.) And also the new sheogorath, who found out how to teleport someone to another random plane, built upon thr Mad Kings mind. (read explanation in one of previous posts.

How can this be explained? :s Is the Amulet of Kings this weak? Or could there be another cult messing with the plane borders again? (Borders=safety wall)