Concepts has three types of “erasers” - Slice, Hard Mask and Soft Mask. As Concepts uses vectors to draw (saving underlying path data for every stroke), none of these act exactly like traditional pixel erasers, but each tool can help you to edit your work in different ways.
 
Slice is a destructive editor - it destroys or “erases” any stroke data it touches, and acts like a razor blade to trim stroke ends or cut your strokes into pieces. As Slice doesn’t create strokes, the only way to undo Slice is to Undo it.
 
Use Slice for…
  • erasing sketches and hand-writing. Make the puck big and destroy the text from the canvas.
  • tidying up plans and designs, including vector files like SVG.
  • editing drawings, leaving natural end-caps to your strokes.
  • snipping single strokes into separate lines you can adjust, including zero point incisions.
  • slicing and shaping fills - slice from an outside edge.
The Hard Mask and Soft Mask are masking tools. You can mask elements of your drawings and adjust the masks for size, opacity and smoothing just like with Concepts' other brushes. Use them with the Shape Guides for perfect block masks. The Masks respond to your pressure sensitive stylus. If this is getting in the way, try using your finger or temporarily disable Pressure settings under Settings > Stylus.
 
Use Hard Mask for…
  • masking parts of your sketch with pixel accuracy,  with a clean, hard edge.
  • trimming images, as Slice does not (yet) work with images. If you want to simulate a crop, you can do it with the Hard Mask and then export. Learn how to do this here.
  • creating masking blocks. Combine with the Shape Guides for perfect shapes.
Use Soft Mask for…
  • blending edges of strokes with other strokes or colors around them. Try using it with various opacities to soften it further.
  • softening the edges of reflections, shadows and brush strokes.