SubBladeReverse is works exactly like SubBlade, except, that the pixels in the indexed range are addressed in reverse order. This can be useful to create zig-zag blades, where the data travels up one strip, than DOWN the other one. Such a blade lets you address all the pixels individually without needing more data lines.
Example, if you have a 100-pixel zig-zag blade:
SubBlade(0, 99, WS281XBladePtr<200, bladePtr, Color8::GRB>()), SubBladeReverse(100, 199, NULL)
Note that you'll need to increase maxLedsPerString to 200. Also, the first LED in the string is counted as zero, so there's always a -1 offset to your numbers to the actual pixels as you'd count them.