Blue Blazes

You call forth four 10 foot cubes of burning blue smoke into any four spaces within range. The smoke completely obscures vision into, out of, or through the affected area, and inside the smoke visibility is 5 feet. When a creature enters the space for the first time in a round or if they start their turn in the smoke, they must make a Constitution saving throw against your spell save DC. On a fail, they take 3d6 poison damage and are poisoned. On a success, they take half as much damage and are not poisoned.

In addition, although the thick smoke makes it impossible to see more than 5 feet without magical means, the burning blue light illuminates creatures that you can see from every angle, granting advantage to melee attacks on other creatures within the affected area.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, the you can conjure 2 additional cubes for each slot level above 3rd.