Oshitsubushi

Oshitsubushi is a technique in life and death problems, where one player forces the opponent into a position where they cannot connect their stones without violating the suicide rule (a move that removes all of your own liberties is not allowed). 

A correct oshitsubushi can mean the difference between life and death for a group.

This move’s effectiveness can depend heavily on rule sets. While we teach by japanese rules that forbid suicide moves, some rules allow self-capture.