You create a wall of fire on a solid surface within range. You can make the wall up to 100 feet long, 30 feet high, and 3 feet thick, or a ringed wall up to 50 feet in diameter, 30 feet high, and 3 feet thick. The wall is opaque, gives off dim light for 30 feet, and lasts for the duration.

When the wall appears, each creature within its area must make a Dexterity saving throw. On a failed saving throw, a creature takes 8d8 fire damage and is restrained by the wall. After it appears, creatures that enter the wall's space for the first time on a turn or that touch the wall must make the same Dexterity saving throw and suffer the same effects on a failed saving throw. If the creature touched the wall, it also takes half damage on a successful saving throw.

Creatures can enter and move through the wall, but they must spend 6 feet of movement for every 1 foot moved through the wall. Any creature that touches the wall or ends its turn inside the wall must make a Strength saving throw, becoming restrained by the wall on a failed saving throw. Any creature that ends its turn within 5 feet of the wall takes 4d8 fire damage, or 12d8 fire damage if its restrained by or inside the wall. A restrained creature can use an action on its turn to attempt to escape. It makes a Strength check against your spell save DC. On a success, it frees itself.

Spells that deal more than 20 cold damage that pass through the wall cause the area of the wall they pass through to freeze into solid obsidian glass (at least a 5-foot square section is frozen). Each 5-foot-square obsidian section has AC 12 and 30 hit points and is vulnerable to thunder damage. Reducing an obsidian section to 0 hit points destroys it. When a section is destroyed, the wall’s lava doesn’t fill it.

This spell ignites flammable objects in the area that aren’t being worn or carried.

If you maintain your concentration on this spell for its whole duration, the wall hardens into permanent obsidian stone and can’t be dispelled instead of vanishing. Without the spell's magic, the destruction of these panels might now cause connected panels to collapse at the DM’s discretion.

At Higher Levels. When you cast this spell using a spell slot of 9th level, the damage dealt by being near the wall increases by 1d8 and all other damage rolls for the spell increase by 2d8.