Alicornutopia

So, when I made Sparkles (Aurum Sadde), Kappa and I needed to come up with a way to move them to another world. Portalsnakes are always available, of course, but we wanted something new. We came up with the Lost Key, a cross between the Subtle Knife from the His Dark Materials trilogy and the key to The Lost Room from the eponymous sci-fi TV show.

It looks like this, and is quite small, as if sized for a child to hold, and came from Esthfora (where she found it is anyone's guess - she may even not have found it yet). As soon as you pick it up, it becomes quite clear that the key is magical. Like the Subtle Knife, when you move it around you get a certain "feeling" that shifts very slightly, and indicates which universe (or, perhaps, type of universe) that particular spot opens to. Some spots don't feel like anything, but if you push the key forward into the air into a spot that does feel like something and turn it, you will unlock a door to another universe. The door looks like a door-shaped shimmer in the air, which you may neglect to notice, and once created, remains there indefinitely. It's not one-way only, but if it's closed, it can only be opened from one side, so if you walk through one such door and it closes behind you, you'll either have to wait for someone else to stumble upon it and open it, or try to find your way back with the key. The feeling that the key gives is much vaguer than the one the Subtle Knife does, however, and it takes much more practice and concentration to be able to consistently find a given universe.

It was introduced here.

Kappa and I reached two conclusions today: opening a new door that intersects an old door on the other side makes the old door disappear, and it's impossible to make doors that intersect on the same side.