Complex sentence: In the "Dungeons and Dragons" role-playing game, driders were formerly dark elves (also known as drow); aberrations that have been transformed from the waist down so they have the body of a spider.
Split into simpler sentences: In the "Dungeons and Dragons" role-playing game, driders are aberrations that were formerly dark elves (also known as drow). These drow have been transformed from the waist down so they have the lower body of a spider.