Running

The Running was an annual ritual of the drow that was about committing a massacre.

Society
The only drow societies that conducted the Running were those who had a physically near access to the surface. It consisted of going to a surface community to kill its inhabitants and pillage the community. It was considered an occasion to "hunt and revel" by the drow.

Procedure
As mentioned above, the Running was an annual ritual. The exact date was often varied by the city for doing otherwise gave them a degree of predictability and with it the danger that the community to be massacred shored up its defenses, for example by buying outside help.

It was expected that young drow who had their first Running combine it with their Blooding ritual.

A side-effect of the Running was that rivals among the drow killed each other "by accident" meaning by taking advantage of the confusion.