We present a novel system of slits, called spiderweb slits, for depth-resolved high energy x-ray powder diffraction experiments. The slits select diffracted x-rays from a gauge volume of a sample while greatly attenuating diffracted x-rays from other sources in the path of the x-ray beam. This capability can be used to block diffraction from battery cell containers, reaction cell windows, or pressure cell windows, thus enhancing many in-situ experiments. High energy x-rays in combination with the depth resolution provided by the spiderweb slits can provide information from specific locations within a polycrystalline material under standard conditions or while working under mechanical, chemical or electric load or extreme conditions. The spiderweb slits function similarly to conical slits or spiral slits, but in this design, select large azimuthal fractions of the Debye-Scherrer diffraction cones for any possible diffraction cone over the area of the slits, while preserving the integrated diffraction peak relative intensities and peak widths, greatly improving performance and versatility compared to previous slit systems. The first slit prototype was applied to several experiments at the X17A beamline at the National Synchrotron Light Source, and these results are presented and compared with ray-tracing simulations. The spiderweb slits will be utilized at the National Synchrotron Light Source II X-ray Powder Diffraction (XPD) beamline.