Cover the entire card surface with patches of bright oil pastel or wax crayon, pressing heavily. Fill every part of the card. The exact arrangement does not matter as long as no white shows.
Cover the entire coloured layer with black oil pastel or crayon, again pressing firmly until the bright colours are completely hidden. This takes time and some elbow grease; do not rush it. The card should look uniformly black when done.
Using the pointed end of the wooden skewer, scratch a haunted house scene into the black layer: a large house with a pointed turret, arched windows with glowing panes, a full moon, bats, a bare tree. Wherever the skewer removes the black, the bright colours beneath glow through.
Fine lines make bats; broader scraped areas make the moon and windows. The more detail scratched in, the more dramatic the result. Keep a sheet of newspaper nearby because the black wax shavings scatter.