how does William's interaction with magic in the woods go?

The book opens with the recollection of a childhood memory by the narrator. It involves a stash of stolen bubble gum, the sharing of this unexpected treasure with the narrator as a young boy, the arrival of the owner of the gum and a menacing threat which fills the young boy with dread and fear of black magic:

“as if a dark cloud had passed over the sun, I felt the great eye of the wizard watching me through the trees. I’d eaten his juju and now his darkness owned me.”