Black Magic is a favourite technique that Steph and I have often used. You can find a tutorial for it here. Basically you take a stamp that has a fair amount of solid area in the image, and stamp onto black card using a white ink. I use Brilliance Archival Ink in Moonlight White. You heat set the ink using a heat gun and then use ordinary coloured pencils to colour in the image and highlight in a few places using a white gel pen to really make the image ‘pop’ against the black background.
Here are some of the cards that we have made using this technique: