Fujihara Tomomi:
OHH!! I just re-checked it, and my brain concluded that Jang Gang sealed the ice stone inside Jang Uk lol. Now my theory with Bu Yeon sacrificing herself is back again, wth -,- Btw did Bu Yeon born with the ice stone, or did she somehow get it inside her body later in life? The relics said she's the ice stone, so it must be before she went missing when she was on the boat holding the stone with Jin Mu, right? But the scene with Jin Mu he said she was able to find it with her power when it was sealed by Jang Gang 10 years ago. Did she pull it out of her body? no way, right? she still has the power to go into the Soul Realm. If she just had to pull it out, why bother going to an isolated place like that? ughhhhh my brain!!!
The relationship between Buyeon and the ice stone it's still a mystery. Let's see what we already know:
1 - 20 years ago Jang Kang knew where the ice stone was (probably Jinyowon since Seolran created the place to store everything malicious people created using the ice stone);
2 - After using the ice stone to switch back his soul with the king, he sealed the ice stone and hid in a different place before fleeing Daeho fortress;
3 - 10 years Jin Mu used Buyeon's energy detecting powers to find where Jang Kang hid the stone. We don't know if the tornado/storm happened due to the attempt to unseal the stone or whatever.