An evil god is rarely just a final boss waiting to be toppled. What I find most compelling is how their presence warps the entire world's logic. Take something like 'Malazan Book of the Fallen'—the pantheon's squabbles aren't background noise, they're the primary tectonic force shifting continents and toppling empires. The plot isn't about mortals deciding to fight a god; it's about mortals trying to navigate, survive, and maybe exploit the cracks between divine conflicts they can barely comprehend. It turns the story from a hero's journey into a desperate, often tragic, game of survival where the rules are written by incomprehensible, malicious beings.
That kind of framework also does fascinating things to character motivation. When the ultimate evil is an active, capricious force in the universe, traditional 'for the greater good' idealism crumbles. Protagonists become pragmatic, cynical, or ruthlessly selfish just to last another day. Their arcs are about preserving some sliver of humanity in a world engineered to strip it away, which can be a lot more haunting than a standard battle narrative. The evil god isn't a problem to be solved; it's the awful weather of the setting, and the plot is about how people build shelters in the storm.
Honestly, I sometimes prefer when the god isn't even directly confronted. The lingering, unresolved dread of its influence often leaves a deeper mark than any climactic divine smackdown.