From a pentagram you launch tadpoles at red, devilish cubes and balls. The aim is to let these figures fall off their platforms. You can collect stars: grab them all! The more tadpoles you 'use', the more points it costs. By the way, you don't have to let all demons disappear to go on to the next level: as soon as you've reached your goal, you can continue.
Hold the left mouse button while aiming, and release to launch the tadpole. You can click on the shapes to see how many points they're worth.