Plot:Tweak palette

From OHRRPGCE-Wiki

tweak palette (red, green ,blue ,first,last)

Color-adjusts a section of the master palette. The first three arguments are the changes to make to the red, green, and blue values of each palette color. For example, tweak palette (20,-30,0) would redden everything, and drop out most of the green. The last two arguments determine what range of colors will be affected. If they are left out, the entire palette is affected. Changes do not take effect until you call update palette or fade screen in. Changes to the master palette last as long as you are playing, but are not stored in saved-games. If you need to make master-palette changes persist in saved-games you will have to use the on-load plotscript trigger.