As a combination

Many hazards will work best as a combination of these approaches. You might start with a detailed description of a trapped chamber, then add a player-facing move for what happens when they try to bypass the trap in a particular way. Or you might write up a series of GM moves and an instinct for a wildfire, plus a countdown describing how the fire spreads. Get creative.

I previously wrote up the ruined crinwin nest—and the climb to reach it—as just a detailed description. I noted that it might do 1d10+3 damage on a fall, but thinking about it more, the fall could easily kill someone or seriously injure them. I want the PCs to know just how dangerous the climb could be, so I write up this custom move:

When you fall from the boughs of the tree, take 1d10+3 damage (ignores armor, forceful) and roll +CON: on a 10+, you're bruised and bleeding and in a lot of pain, but miraculously nothing's busted; on a 7-9, something's broken—ask the GM what; on a 6-, you landed bad and you're at Death's Door.

Sajra's lair is an old Green Lord tomb, and the mummified Maker is still ensconced in its central vault. To reach the vault, one must pass through the Hall of Humility and the Hall of Gratitude. They are warded with Fae magic to ensure that those who approach the vault do so with proper respect. I decide to write these hazards as custom moves.