A swirling cloud of embers and smoke fills a 20-foot-radius Sphere centered on a point within range. The cloud’s area is Heavily Obscured. It lasts for the duration or until a strong wind (like that created by Gust of Wind) disperses it. When the cloud appears, each creature in it makes a Dexterity saving throw, taking 10d8 Fire damage on a failed save or half as much damage on a successful one. A creature must also make this save when the Sphere moves into its space and when it enters the Sphere or ends its turn there. A creature makes this save only once per turn. The cloud moves 10 feet away from you in a direction you choose at the start of each of your turns.
RollQuest ships the D&D 2024 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.