lirael erase tracks

Lirael ran to a snowdrift, sat down in it, and started to drag snow across herself. Soon she was almost completely hidden, save for the line of footprints that led across the snow to her hiding place.
Quickly, Lirael visualized the Charter, then reached into its eternal flow to pull out the three marks she needed. One by one they grew into brilliance inside her mind, filling it until she could think of nothing else. She drew them into her mouth, then puffed the marks out towards her tracks in the snow.
The spell left her as a whirling ball of frosted breath that grew until it was an arm's span wide. It drifted back across her path, sweeping her footsteps clean. Then, its work done, the ball let itself be taken by the wind, breath and Charter marks dissolving into nothing.

Lirael, Ch. 3, pg. 32