Fire Shield

4th-Level Evocation Spell (Druid, Sorcerer, Wizard)

Casting Time: Action
Range: Self
Components: V, S, M (a bit of phosphorus or a firefly)
Duration: 10 minutes

Wispy flames wreathe your body for the duration, shedding

Bright Light is normal illumination. See also Exploration.

in a 10-foot radius and

An area with Dim Light is Lightly Obscured. See also Lightly Obscured and Exploration.

for an additional 10 feet.

The flames provide you with a warm shield or a chill shield, as you choose. The warm shield grants you

If you have Resistance to a damage type, damage of that type is halved against you (round down). Resistance is applied only once to an instance of damage. See also Damage and Healing.

to Cold damage, and the chill shield grants you

If you have Resistance to a damage type, damage of that type is halved against you (round down). Resistance is applied only once to an instance of damage. See also Damage and Healing.

to Fire damage.

In addition, whenever a creature within 5 feet of you hits you with a melee attack roll, the shield erupts with flame. The attacker takes 2d8 Fire damage from a warm shield or 2d8 Cold damage from a chill shield.

Source: Player's Handbook, p. 274