The 6 eyed skeletal dragon-snake like demon is an art I've made and also used it for a boss in a Duke3d Mod that I've contributed few levels including this huge boss.
The art is the real version I've made, took forever to make that thing.
Also made this version that is over a firepit and has all the lighting effects on it etc.
That thing is also a boss of the forgotten pyramid in a Duke3d Mod my friends and I worked together.
I contributed some level and I designed the boss as well.
Video of fighting it
background credits : https://upload.wikimedia.org/wikipedia/commons/6/65/The_Door_to_Hell.jpg