Writing grim portents

If you're having trouble coming up with grim portents, look at the GM moves for the threat type. If the threat is a monster or a follower, look at their moves, too. Those moves represent what the threat does and how it causes trouble. Use them—along with the threat's instinct—to inspire your grim portents.

Here's another trick: work backwards. Start at the impending doom, and ask yourself "What discrete, observable event would happen just before this? What would the situation look like?" That becomes the last grim portent. Then, what would happen before that? That's another grim portent. Keep working backward until you have a grim portent that's visible from the current state of things.

As you write your grim portents, you'll probably find yourself changing your mind and maybe even rewriting the impending doom. That's fine! But try to keep things loose; a high-level outline is way more useful and flexible than a detailed plan.