or solve online (using our beta test of Penpa-Edit tools; use tab to alternate between a composite mode for line/edge drawing and a letter entry mode.)
Theme: F is for Fiendish
Author/Opus: This is the 4th puzzle from guest contributor Carl Worth.
Rules: Divide the grid into 20 pentominoes so that no two pentominoes of the same shape (including rotations/reflections) share an edge. A cell with a letter in it must be part of the pentomino shape normally associated with that letter. An inventory of possible pentominoes is given below the puzzle.
Answer String: Enter the letter associated with the pentomino occupying each cell in the marked rows from left to right and in the marked columns from top to bottom, separating the groups with a comma. Use CAPITAL LETTERS!
Time Standards (highlight to view): Grandmaster = 4:30, Master = 10:00, Expert = 20:00