Who can use it: Anyone except the person playing the main character.
When you can use it: In response to the ritual phrase, “That sounds difficult.”
What it does: In order to do the thing the person playing the main character described, she must spend another moment of awareness. If she cannot, then she cannot do the thing she said and must change it.
As always when spending a moment of awareness, someone playing a character present in the encounter can help by spending awareness on her behalf, which would allow her to accomplish the thing she described. Provide some description of how you provide help.
Effectively this increases the cost to two moments of awareness, but the player pays each one separately, and all the rules about spending a moment of awareness (like helping) apply to each one separately.