Wall of fire

Wall of fire was an evocation or conjuration spell that raised a one-sided opaque curtain of flames in the form of a segmented wall or a circle. After the Spellplague, the wall was two-sided.

Effects
The wall was oriented vertically with respect to the caster and did not move once created. The shape and the flaming side of the wall was determined by the caster and the maximum size of the wall was determined by the caster's level. The sheet of flame lasted for as long as the caster maintained concentration, or for a minimum time if the caster became distracted. The opaque curtain appeared up to 20 ft (6.1 m) high and reddish-blue to violet in color if created by arcane magic  or greenish-yellow to amber if created by divine magic. After the Spellplague, a wall of fire was limited to 40 ft (12 m) in length, made up of 5 ft (1.5 m) orthogonal segments, and only lasted a few seconds. The range of this spell was 50 ft (15.2 m).

Any creature near the flaming side of the wall was subject to harm from the heat, although the farther away, the less intense the heat. Any creature passing through the wall suffered greatly&mdash;undead and other creatures susceptible to fire got the worst of it. Post-Spellplague, a creature passing through a wall of fire was also slowed by a few steps.

Components
Verbal, somatic and material components were required to cast this spell, including a small bit of phosphorus for arcane casters. Divine casters could use their divine focus or holy symbol. Some druids used mistletoe as the material component of their spells.

Realmslore
In the Year of the Prince, 1357 DR, the drow wizard Kilili cast a wall of fire to hold off some warriors threatening the mage Parwyyd Hanifar.