“ Serpens Necto is a mask made of snake skins stitched together and crudely painted in white. With this on a person can bind people to their will under the right conditions. In darkness the effect of the mask is greatly enchanced by illumination from under by a candle.”
“ (Apologies to GRRM and HBO)
A group of northerners want to bring the Old Gods back to the south. They grow cuttings from the white trees seeking the blessings of the Old Gods on the project, and when the saplings are big enough, they carve faces in them and secretly plant them in forests all over the south, to extend the 'reach' of the Old Gods.
The plan works of course, but the trees are *baby gods*, and behave as such when invoked.”