We know that the five-stage structure of the plot is formed by the following order of events: exposition, rising action, climax, falling action, and resolution.
And, we can see that in the short story, Tom describes the power of a character created by Ben. After that, Ben clarifies how the character is not powerful but kind of cursed, intending to change Tom's idea. In this way, we can see that the plot is about to change its course, since now the idea of the character has taken another way.
So, the discussed stage in this passage is climax (also called "the turning point"). It is the stage in which the highest point of tension takes place, leading the reader to wonder what will happen next.