Siamese Finned Franken Whale
Uses equal-sized groups of rows, columns, or boxes where one digit appears only across the other group.
All candidates have been entered in the empty cells.
Any true candidate 3 in A conflicts with 3 in cell C. The case with no true candidate in A is proved below.
Any true candidate 3 in B conflicts with 3 in cell D. The case with no true candidate in B is proved below. Remove candidate 3 marked × in cell C and cell D.