Hellbook is a heroic tier feat.
Prerequisite: Tiefling, wizard, Spell book class feature
Benefit: Each time you take an extended rest, choose one daily wizard attack spell that has the fear or fire keyword and that is currently in your spellbook. As a minor action, you can swap one prepared but uncast daily wizard attack spell for this chosen spell. The level of the uncast spell that you swap out must be equal to or higher than the level of the chosen spell.