You conjure a 10 foot square pit, 10 feet deep and filled with flames, on ground that you can see within range. Creatures stood on the area of effect must pass a Dexterity saving throw. On a success they can use their reaction to move 5 feet out of the area. If they fail, or are unable to move out of the area, they fall into the pit. Subsequently, creatures shoved or otherwise moved into the area will fall into the pit.

A creature falling into the pit takes 1d6 bludgeoning damage from the fall, and 2d6 fire damage from the flames. A creature starting its turn in the pit takes 2d6 fire damage. Climbing the wall of the pit requires a Strength (Athletics) check of DC equal to your spell save DC.

Ritual

When this spell is cast as a ritual, the duration becomes Concentration, up to 1 hour. If an incapacitated or bound creature is placed into a ritual pit of flame, they will hover above the fire without taking damage. Charisma (Intimidation) checks made against this creature have advantage. If the creature subsequently is no longer incapacitated or bound, it can move away from the pit. The ritual pit of flame has no effect on creatures that are resistant or immune to fire damage.