This “tricky little charm” makes the paint on a banner flash different colors.
References from the canon
- Hermione used this charm on the banner that the Gryffindors had painted on one of the sheets Scabbers had ruined. It said Potter for President, and Dean, who was good at drawing, had drawn a Gryffindor lion under the words (PS11).
- It is probably this charm which Hermione used to make the various squares on their revision schedules flash different colors as they prepared for O.W.L.s (OP29).