✷Wisps have no power, except over those they make a deal with. One cannot wish to curse or heal someone else, because that would require the wisp to exert power over another person. One can wish to have the power to curse or heal others.
✷The price of a wish often reflects the nature of the wish itself. Greater wishes will cost more. More specific, limited wishes will cost less. Wish wisps will not grant wishes that the character is unable to pay for.
The above rules are for the benefit of players. They are not necessarily common knowledge to the characters in this RP, though the Wisps have been around long enough that at least rumours of what they can do and what they are like has spread among the populace.