Go back to 5e - Spell Focus Mastery Properties.

🎩5e - Expand🎩

While holding a 🎩Spellcasting Focus with the Expand property, spells you cast with an 🏔️Area of Effect, you increase that 🏔️Area of Effect by 5 feet in size. A radius of 20 feet for example, would become 25 feet, a cone with a length of 15 feet becomes 20 feet.