“ A legend tells of a people living deep in the desert, they appear at first as ordinary human beings, sometimes impersonating someone familiar to the PCs, before causing their features to disappear, leaving a blank, smooth sheet of skin where their face should be.”
“ (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.”