Also Diablo 1 images are 16-bits colors, those white areas looks like the 32-bits error that windows give me when I launch diablo 1 with it.
I haven't quite figured out how to get proper animations of the Uniques, such as the doom guard, Rustweaver.
As I said earlier in the thread, each monster-type has multiple color palettes; each one corresponding to a different variant of the monster. They do something apparently more complex for the Uniques, and I haven't discovered what that is, yet.
I found something about the Unique monsters colors
"Uniques have their own set of TRN files that will not work for normal monsters. Use of normal monster TRN files on uniques is unknown."
Seems Unique colors are on those .trn