Duskfall

You place your material components on the ground, forming a circle with the candles and placing the coal in the center. When the casting is complete, the candles melt away into nothingness and the spell takes hold. For the duration, a 1-mile radius sphere centered on the point of casting becomes affected. Sunlight can’t enter the area and other light, both magical and mundane, can only create dim light. No bright light can shine in the area. In addition, fire can’t burn as hot as usual, causing it to deal only half its normal damage within the area. Casting this spell on the same spot every day for a year makes this effect permanent until dispelled by a casting of dispel magic using a spell slot of 7th level or higher.

At Higher Levels. When you cast this spell using a spell slot of 8th level or higher, the radius increases by 1 mile and the duration increases by 8 hours for each slot level above 7th.