[It's the magic that keeps him from finding her once she's gone, the strange unfamiliar power, and that scares him. To not find her, at a time like this, to not be able to feel where she is... it sends Syaoran out into the blizzard without second thought. He keeps looking, searching, unaware of just how far she had wandered, how much the event is keeping her from him.
And, of course, when he's finally close enough to feel her, the monster's presence is all too clear.]
Sakura!
[Syaoran doesn't let himself hesitate--summoning the magic at his disposal, and directing an attack at the monster. It might not be an instant kill, but it will hurt the creature, and should at least get the attention and danger away from her.]