Possible Clues:

• This madman messed up tsarina endlessly
• Artists included a monk
• Puritans confounded by sinister Russian
• Notorious Russian monk embraced by puritans
• Monk artist's included
• Notorious Russian monk at court of Tsar
• Russian peasant and self-styled religious elder, born approx 1870, died 1916
• Infamous Russian mystic
• Masters enter court fixture?
• Russian who gained power when installed by tsar ultimately