Blocked Collage was also a Technique Lover Challenge back in 2005.
In this challenge it was shown as a reverse Masking technique. The link in the challenge thread does no longer work.
Cut out a shape (circle, oval...) out of scrap paper. Center shape cutout over your card. Sponge ink from the edge of the cutout in towards card center. Stamp your images. Take off scrap paper. Easy peasy! It makes very simple and elegant cards.
Check out the challenge cards
here.