Preparations.
Hiems will take, say, 2 different pieces of wood in the house, mark them in different ways, and take a shard in both. He does this in silence, quietly, as if none of that mattered really. And maybe that's the case.
He'll then give the larger pieces of wood to Viscaria.
- Fair Lady, I entrust you with these. Hold them close to you. If all goes well, I'll try to warm up that piece of wood, so you'll know you may come. If there's danger and you need to prepare, I'll warm the other. If none of them warm, you should assume that I'm either dead, or outside the normal limits of Hermetic Magic. I'll only be able to do this for a brief moment, so don't lose track of them.
Still cool as ice, Hiems prepares a ceremonial casting space, taking all the time he needs. Then, he begins incanting loudly, exageating his gestures, and, more importantly, drawing on his inner strength. The air in the room noticeably cools as he cast his spells
Hiems will first spont a personnal-range version of "Lungs of the Fish" (lvl 15 MuAqAu), using life-linked spont magic:
Muto 1 + 0 + Sta 2 + + Artes Liberales (ceremonial Magic) 2 + Philosophiae (Ceremonial Magic) 2 + Booming voice and gestures 2 + 1d10=5 = 14/2 = 7. He thus must use 2 more fatigue to go up to 15.
He'll then sit quietly, resting until he feels fine again, which takes about 30 minutes.
Then, he goes to the same spot, and incants again, sponting a spell that'll avoid him to fall should the other side be in the air: ReCo, I guess same base as "rise of the feathery body", personnal range, duration sun.
Re 7 + Co 5 + Sta 2 + Voice and Gestures 2 + 1d10=1, 1d10=7 = 16 + 14 = 30/2 = 15.
2 minutes later, he's recovered.
- I'm almost ready. If some of you have warding spells you may cast on me, I am ready to lower my parma.
When everyone is finished, he'll then cast his "Endurance of the Everlasting Cold" and "Sidestep the sight". And step through the mirror.
He doesn't intend to die, for a lady might be in danger. But if he dies, he's fine with it.
At least that's the plan.