Deflection

A deflection forces a defender away from its duty. Every defender has a job: it guards a piece, covers a square, holds a rank. Give it something it must answer, a check or a capture it cannot afford to ignore, and it has to abandon the job. The thing it guarded falls one move later, often to a piece that was already attacking it.

What makes a deflection WORK is overloading: the defender cannot do both jobs. A rook that guards the queen AND the back rank will answer a back-rank check and leave the queen; a king that is the only defender of the queen next to it will step away when checked. So the checklist is: what does this piece guard, what would fall if it were not there, and what forces it to move?

The way to spot one is to look at the target first. A piece defended exactly once is a candidate; then ask what its single defender would rather not ignore. Checks are the strongest lever, because a check must be answered on the spot, and the king is the easiest piece to deflect: it never gets to say no.

Above 1600 the deflection is almost always a sacrifice. You pay a rook, without check, to pull a rook off the eighth rank, and the absence pays back a queen. The higher the level, the more the deflection prepares the blow rather than being the blow itself.