For a handmade brush painting of a horrible satanic snake, consider the following color combination:

- Base color: Deep, ominous black for the snake's body, representing its sinister nature and association with darkness.
- Accent color 1: Blood-red highlights along the edges of the scales and in certain areas to evoke a sense of danger and malevolence.
- Accent color 2: Sickly, toxic green for the eyes and any additional details, symbolizing the creature's connection to the underworld and its eerie, otherworldly presence.
- Background: Shades of dark purples and blues blended together, with hints of fiery oranges and yellows creeping in from the edges, creating an atmosphere of ominous foreboding and supernatural energy.

This color palette will help to convey the ominous and satanic essence of the snake while allowing for striking contrasts and a sense of dark allure.