Create a dark fantasy scene featuring a large fiery green demonic portal. The portal should swirl with toxic green flames, smoke, and chaotic energy, surrounded by jagged black stone, cracked earth, and glowing runes. The aura should feel ominous and corrupted, with drifting embers, shadowy tendrils, and a sense of something powerful trying to break through. The overall mood is dark, infernal, and otherworldly.