A cone shoots out from you in a quarter circle on the grid. When you aim a cone, the first square of that cone must share an edge with your space if you're aiming orthogonally, or it must touch a corner of your space if you're aiming diagonally. If you're Large or larger, the first square can run along the edge of any square of your space. You can't aim a cone so that it overlaps your space. The cone extends out for a number of feet, widening as it goes, as shown in the Areas diagram. For instance, if you cast the breathe fire spell, you create a cone of flames that originates at the edge of one square of your space and affects a quarter-circle area 15 feet on each edge.

If you make a cone originate elsewhere, use these same rules, with the first square of the cone using an edge or corner of that creature or object's space instead of your own.