Do you really need this move?

Whatever you intend your new move to reflect or model, how would you handle it in play without this new move? Would it even be possible? What questions might you ask the PCs? What GM moves might you make? How might the PCs respond? What existing player moves might that trigger? How would those moves likely play out?

If you realize that you don't need a move, great, you've just saved yourself some time!

If you move forward with writing a move, you've now got a benchmark to measure your move against. If it doesn't improve on what you'd do with the core loop, GM moves, and existing player moves, then why are you writing it?

The PCs are planning to take the Fae paths again (to find and destroy the tether of the shadowy presence that haunts the Great Wood). They'd prefer not to indebt themselves to Thornthumb again, and so they intend to access the waystones by taking hallucinogenic mushrooms under a full moon.

There's already a move for walking the paths once they access them (Book II), but I'd like a custom move to resolve what happens when they take shrooms together in the Great Wood. (Hey look, a trigger!)

Because I expect to use this move only once or twice, I don't want to spend too much time writing it. But I am willing to spend a fair bit of table-time using it. It shouldn't overlap significantly with the "walking the paths" move. And, oh yeah, Rhianna's bringing her crew, so I need to account for them.

Not all of my players have experience with psychedelics, so I'd like the move to model how a shroom trip might go. The move should also communicate the stakes and risks of taking shrooms, especially in a haunted forest! And because shrooms can bring strong emotions to the surface, this seems like a great time to explore the PCs' inner feelings.

Without a custom move, I'd probably fall back on having everyone Defy Danger with CON or WIS, the danger being that they get sick or overwhelmed or have a really bad trip. Then I'd probably prompt them to Keep Company while hallucinating. Which ain't bad, but I bet I can do better with a move!