On a night of your choosing, whether the weather reflects it or not, fog will billow in under the doors of whatever room Yuri is in. It will become so thick that it'll be hard to see more than a foot in front of him, and a woman's voice will be heard as if she's standing right beside him.

"I always enjoy the gifts my pets leave me."

The fog grows more dense, pulling away from the edges of the room and surrounding only Yuri.

"Let me give you something in return."

When he next breathes in, all the mist around him will rush into his system at once, causing him to pass out. Upon waking he'll find himself in his new home with all his things moved and his new power in place. As for the carapace, it will have started growing - and the rest of it growing in will not be painless.