The two volkhvs of Beloozero
During a famine around Rostov, two volkhvs from Yaroslavl went along the Volga claiming that noble women hid the harvest; they cut open the women's shoulders and 'drew out' grain and fish, killing many, until the tax-collector Yan Vyshatich captured them at Beloozero.
1071 CE · 60.03, 37.78 · status: account
The account
The Primary Chronicle (entry for 1071) gives a long interrogation in which the volkhvs explain their cosmology: God washed himself in a bath, wiped himself with a rag and threw it down, and Satan made man from it. Yan handed them to the relatives of their victims, who killed them and hung their bodies from an oak. Historians link the episode to Finnic and Slavic harvest magic in the north.
The sceptical view
A one-sided Christian source; the 'drawing out' of food was presumably a ritual trick.