Sometimes the square your skewering piece needs to reach is guarded. The techniques for coping with this really are no different than the methods for loosening a forking square, a pinning square, or any other square you need to make safe, but it will be useful to see how they look in this context. Here we also will consider some related issues: cases where your piece finds its path to the skewering square blocked, or where its guardian’s path to the skewering square is blocked.
Remember: if the two enemy rooks are on the same diagonal, they're poised to be skewered. Thus in the frame to the left the arrangement of Black’s rooks looks inconspicuous, but since neither of them can afford to be taken by a bishop they are inviting prey. White reaches for his dark-squared bishop to play it to a5. But there is a complication: the square is protected by Black’s queen. How to cope with this? The answer is easy: White exchanges the defender away with 1. QxQ, b7xQ. Now Ba5 wins the exchange after one rook moves to protect the other.