Downfall Control is a Ritual added by Roots. When performed, it will summon rain if it isn't raining, or banish the rain if it is.
Each Downfall Control Ritual requires a Lily Pad or a Wheat to be placed on the Casting Altar, and one Vine and one Old Root to be burned in the Incense Brazier. The Ritual requires Mundane Standing Stones to be placed around it.
Runic Tablet entry