The Idol is an adventure map structure in the Heroes of Might and Magic series.
In Heroes II, the idol provides +1 luck for the next battle that the hero fights. This only last for one battle, and only for the hero who visited it. There is no battle, and it is free to visit.
In Heroes III it provides +1 luck on odd days of the week, +1 morale on even days, and both on the seventh day. The effect lasts for the next battle that the hero fights.