Impossible spells are counted separately from a caster's list of learned spells, spell repertoire, or similar spellcasting class features. They are in a separate list of their own and don't consume a spell slot when cast. While most impossible spells are simply recorded as knowledge within a book, it's possible for them to exist in the form of a scroll, wand, staff, or other magical implement. Even in such forms, the power required to cast an impossible spell means only trained spellcasters can use the item. The items are also always consumed in the process of casting the impossible spell, preventing it from becoming an artifact or relic that can be passed on easily.

Fueling: The impossible spell can be further fueled by the caster pouring more of themself into the spell to make it more powerful. After casting an impossible spell, the caster can use the Fuel Impossible Spell action.