Scroll of Extension

Scroll, uncommon

This blank scroll can be inscribed with a spell you have prepared of 4th level or lower, taking 1 hour.

When you cast that spell with the scroll of extension in hand, as a bonus action you can double the spell’s duration. This causes the scroll of extension to go blank, and a new spell cannot be inscribed on it until you complete a long rest. The scroll has no effect on spells with a duration of instantaneous or permanent, and while it doubles the maximum duration of spells that require concentration, ending concentration still ends the spell.

Each time you extend a spell with the scroll, roll 1d20; on a roll of 1 the scroll turns to ash rather than going blank.