As an action, you can decrease the amount of light emitted in a 1-meter radius within 5 meters. You can decrease the light level by one step (from bright light to dim light, dim light to no light).
The change in illumination can be gradual (taking as long as 1 minute) or sudden (occurring immediately when you cast this spell). You can alter the level of illumination from its original level at any time during the spell’s duration as an action.
You can gloom up to three areas at a time and dismiss a gloom on your turn (no action required).
When you cast this spell, or as an action on a later turn, you can cause a gloomed area to engulf a creature within 1 meter of the gloom. The creature must make a Fortitude saving throw.
On a failure, it takes 1d6 necrotic damage and has disadvantage on the next attack roll it makes before the end of its next turn.
On a critical failure, it takes twice as much damage.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
After the gloom engulfs, the gloomed area ends.
At higher levels
This spell’s damage increases by 1d6 when you reach 9th level (2d6) and 17th level (3d6).