Charred Soil

You create a 20-foot-radius circle of burning, hot soil centered on a point you can see. The ground becomes difficult terrain and stays hot for the duration of the spell.

Each creature that is standing on the charred soil at the start of its turn must make a Constitution saving throw against being burned. On a failed save, the creature gets burned for 2d4 fire damage and spends its action escaping from the hot soil. On a successful save, the creature takes only 1d4 damage and may move on the difficult terrain. Creatures that have fire resistance are immune to the soil.

A bucket of water can extinguish the soil, making it traversable again.