Create an image of a detailed concept skin for the **ACE32 assault rifle

Create an image of a detailed concept skin for the **ACE32 assault rifle**, named **Abyssal Fang**. The gun should be forged from dark obsidian stone with intricate, glowing cryptic runes etched along its body. The skin's primary colors are deep black and smoky grey, with subtle accents of dark crimson to highlight its menacing aura. The design should exude a gothic and ancient feel, with the texture resembling cracked obsidian, and the glowing runes should pulse as if channeling dark energy. The barrel and stock should have sharp, angular lines to give it a more aggressive, ominous appearance, fitting for a weapon of a dark overlord.