Question: why maa kali drink blood?
Answer: In Devi Mahatmya, Kali unfurls her tongue in her role as the ultimate deliverer called upon to salvage a situation that seems hopelessly out of control. She is summoned by Durga herself to destroy the demon Rakta-bija, whose name means 'blood-seed'. ... After killing the demon Daruka, Kali drank his blood.