This spell can be cast on an unengaged enemy unit within 30". If successfully cast, the target unit is enveloped in rain and gets a soaking.

A soaked unit suffers a further -1 modifier on its shooting rolls to hit. If the unit does not fire using BS (a cannon, for example), then it may only fire if the player can first roll a 4+ on a D6 each turn.

This is not a remains in play spell as such, but units that have been soaked suffer the effects for the rest of the battle. There is no additional effect for being soaked more than once.