Cliff Childs provides us with a rich illustration of a spidery-limbed giant emerging from a swamp. It's a figure that evokes a sense of calculating menace and control. Like an alligator, this creature lurks and waits for the time to strike. It's easy to believe that this thing has deathtouch.
The colors are low-saturation, which gives it the gritty feel of rotting foliage. As things decay, they tend to lose their color. You can see that leeching process reflected in the murky swirl of dark greens and brownish-greys. People often confuse "good color" with "vibrant color." The palette choice doesn't have to assault your eyes to be good. Subdued tones like this have a different feel to them, and can be as expressive as any neon hue.
The anatomy of the creature is nice, too. The front limbs look lobster-esque, and the quills on its back make it look bulkier and fiercer than it is. The perspective hides the full creature from view, obscuring it with atmospheric fog. Is the spooky fog worth the tradeoff of seeing less of the creature itself? Sometimes less is more. The monster you see is rarely as scary as the one you imagine lurking in the darkness.
The most important thing is that the image looks like the abstract game mechanics it represents. This visually feels like an organism of both black and green, rot and foliage, and it looks like landscape given life. The foggy background and wire-thin limbs look like something that could strike with deadly precision.