Consider this position:
In addition, White has a knight somewhere and black has dark-squared bishop. Can you give the calculation of corresponding squares - for each position of the knight where should the bishop go if black wants to save himself?
Here is the beginning of the calculation: to win, the knight must play Nb3# or play safely Nxe3. Thus black must prevent the knight from reaching safely c1,e3,d4,a5 or c5. If white plays Nd3 then black must play Ba3, to guard c1 and c5. If white plays Nc6 then black should play Bc3 (protects d4 & a5); if then white plays Kc1 then black plays Bd2+ or Bb2+, and then comes Kc2 Bc3, returning to the initial position. If black had played Bb6 (which - like Bc3 - protects d4 and a5) as a response to Nc6, then Kc1 wins. So the only answer to Nc6 is Bc3. If white plays Ne5 then black plays Bb4 (to answer Nd3/c4/c6 with Ba3/d2/c3). And so on... can you continue the calculation?