How Not to Summon a Demon Lord

Storm the Church (2x9)

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Diablo and the others are locked up in the sanctuary by Vishos and kept apart from Lumachina. Meanwhile, Horn managed to escape, but she's torn between her desire to flee all by herself and her desire to help her friends. That's when Babalon, the Level Up Goddess that resides within the Holy Grail, appears before Horn.