Nightmare. You inflict disease upon your enemy, causing their flesh to rot and fester.
As a bonus action, you can inflict grievous, festering wounds upon your foe. The next time you hit a creature with a melee weapon attack, you deal an extra 2d6 + your proficiency modifier of necrotic damage. At the start of each of the creature’s turns, they must succeed on a DC 13 Constitution saving throw or take an additional 1d6 necrotic damage. On a success, they take half damage, and the effect ends.
You can use this ability once before refreshing it in town using Performing Sacred Rites or Religious Service Downtime actions.
At Higher Levels. The attack deals an extra 1d6 necrotic damage and the ability DC increases by 2 when you reach 5th level, 10th level, 15th level, and 20th level.