After a moment he sticks his head over the side, mutters "Heiss!" and wiggles his fingers at Promise. The clothes feel a good deal warmer. He retreats back to his hillock.
Ari is happy! He does more work.
He pokes his head over again. "Can I get another cup of your blood when it's time to make the cottage? It'd be very handy."
"Yeah, should be easily enough for this. I might want more to make the underground workshop and the bigger house, but that's a while off. It's a pity blood loses its potency so quickly, I could use that stuff for everything if I got a stockpile going."
Promise warms up and feels out the harmonics of the area, occasionally testing small spells with no lasting effect (lights and little gusts of wind) to see how she's doing.
Ari occasionally pops in for progress checks and to warm up her clothes. He makes a lot of progress on the cottage spell, which is substantially easier with such an energy-dense power source.
"I think I know what I'm working with now. Where are you going to put the cottage and where should I put my warmth circle relative to it?"
"Doesn't much matter to me, there's no ley lines here or anything. You can put the warmth wherever and I'll work around it. Is it spherical?"
"Cylindrical. I could do a sphere if that would be more convenient for some reason?"
Since he doesn't seem to care where she puts it, she puts it right where she is. There is a faint whoosh as air pressure changes. Snow in her vicinity starts melting; she pulls his shirt off so she can free her wings, hover, and get his pants off without getting them wet, and hands them over.
Ari gratefully accepts his clothes and places them neatly into his backpack.
"Yes please. Even if I can't do it, it might be important if I'm going to do any sorcery that interacts with it."
Ari makes a valiant effort to explain it! He is pretty terrible at that, but it's possible Promise will be better at following along than Tacky Creep.
That will certainly help, though perhaps not as much as it should. Ari isn't great at answering clarifying questions. But he tries!
Promise quietly concludes that he is not an ideal teacher, but if he does try she can eventually triangulate what she expects to need to know for sorcerous purposes.
He gets to where he is now. "So really, all I need to get done is the safeties that keep the house from exploding like that illusion back at Tacky Creep's house did. Because that would be bad."