Heart of the Night

No, there isn't a 5th-level spell there. Maybe it's with the guardian. I ran through the entire map using spells that cause confusion/slow/weakness. When I defeated the dark elf (almost at the very end), I got Berserk. None of the spellbooks give it. The elf has it, but the discussion doesn't concern it. Yes, there was also a Blind spell, and it was quite early, but it's level 4. As for summoning, the elf was given Heavenly Shield and elementals - both are useless. Later, in the Necropolis, I got a Wall of Swords, and it turned out to be more useful for closing gaps in the castle.