Anyone can join, with a 50-word vignette in the comments. Your vignette does not have to include the prompt term.
"A bit," said Halley, firmly. "The secret of controlling the nightmare lies in the bit."
Corridon snorted. "Can't be an iron one. It's still a fae horse. Iron would be the death of it."
"That would be a blessing," said Artos hotly.
"If," said Corridon, "it would let iron near."