It's the kind I hope you never need. These are meant to seal demons too powerful to banish or defeat outright. I should tell you how they work, but... maybe that should wait until you can try to use them, yourself. In the meantime...

[He looks around the room, as if just realizing where he is now. Even if she's a tiny right now, the thought that he's in her bedroom makes him blush a bit, the same way going in Mina's room had when he was younger.]