Smoking Plate of the Dwarvish Warlord

Armor (platemail), legendary (requires attunement)

You gain a +3 bonus to AC and are resistant to cold damage while wearing this armor.

Additionally, when you are struck by an attack, you may use your reaction to fill a 20-ft. cone in front of you with heavy smoke. In addition to the normal penalties applied from being in a heavily obscured area, creatures that start or end their turn in the smoke must succeed on a DC 15 Constitution saving throw or be poisoned for 1d4 rounds. The cloud disperses after 2d4 minutes. A moderate wind (11–20 miles per hour) can also disperse the smoke after 1 minute, and a strong wind (21 or more miles per hour) can do so after 1 round. Once expended, this property of the armor cannot be used again until the next dawn.