First, I'm going to set up what's called a ward. It's a barrier, not a prison. You can cross the line any time you want, but you'll break it and I'll have to set up another. It isn't supposed to contain you. Only your magic. We can do this every night, if it works.

[There are different kinds of wards, but Rosethorn wants to be very clear that this isn't a punishment for Elsa. She has no intention of trying to keep the girl locked up, and she's very deliberately only blocking magical power.

She takes the appropriate jar from her mage kit, opening it. She uses its contents to draw a line around the edges of a good portion of the room (Elsa included.) Rosethorn leaves enough space to move one of the mattresses onto the floor for herself if Elsa's more comfortable sleeping in the wards on her own.

And then she closes the circle, feeling the magic snap into place and sending up a silent prayer that Elsa's magic stops at the barrier between them. It should. At least the difference will be easy to see, with all this snow falling.]