Block X+3, where X is the Distance between you and the source (Count the shortest number of squares between you and the target, then prevent the next X+3 damage you would take this initiative)
Block X+2, where X is the Distance between you and the source (Count the shortest number of squares between you and the target, then prevent the next X+3 damage you would take this initiative)
Block X+1, where X is the Distance between you and the source (Count the shortest number of squares between you and the target, then prevent the next X+3 damage you would take this initiative)