Studying life and death problems that are not too difficult is regarded as the best way to develop and sharpen reading and visualization. It is the main target of this book to help you develop these skills as well as acquire factual knowledge. In 52 chapters, an in-depth analysis of the most frequently occurring corner shapes and their origin is presented. Each chapter consists of four problems of varying difficulty that are usually based on the same basic shape. Most chapters offer a step-by-step approach where an otherwise difficult-to-solve problem is deconstructed into two or three easier problems. The solution section analyzes the most relevant variations and failures, as well as typical mistakes by both players. Three appendices cover important, all too often not sufficiently understood aspects of bent-four in the corner, the ten-thousand-year ko, and the approach move ko. In this revised and expanded edition -a first version was published for promotional purposes-, each set of problems is also analyzed in video format accessible via QR code in Yoon's Baduk Café. All the problems are relevant to actual combat situations and the knowledge gained by working through the book will both benefit Kyu and Dan players.