dissolve

On the click, blotches appear all over the page and merge into a dark cover, with a glowing rim in the accent colour. Once the next page is ready, smaller holes burn through in other places, glowing at their edges, until the page is uncovered.

A shader compares a noise pattern with a level that rises as the cover goes on, and colours a thin band along the edge. The reveal uses a finer pattern, so new holes open rather than the blotches shrinking back.