Concentration Lines are a classic cartooning technique used to create movement on the page, draw the reader’s attention to a specific panel, and more.
While they are difficult to freehand, MediBang Pro makes them easy to draw with this handy tool.

Creating

From the Filter, select Concentration Lines. A new Concentration Line will appear on the canvas.
You can use the adjustment panel as seen below to move the Concentration Line around on the canvas.

Adjusting

You can also control the length, thickness, and density of the lines to create different effects.