Umbral Slide

While strumming a powerful chord or pounding a sonorous beat you call upon the Shadow Weave. Encasing yourself in purplish flames your propel yourself forward, sliding on your knees 30ft. Any creature in the path must make a dexterity saving throw against your spell save DC or take 2d4 Necrotic damage on a failed save, or half as much damage on a successful one and can't be healed until your next turn. At the end of your slide you release a 10ft radius explosion of of purple flames, creatures in the radius must succeed a Constitution saving throw against your spell save DC or take 6d6 Necrotic damage on a failed save, or half as much damage on a successful one and can't be healed until your next turn.
Increase the number of damage die 1 for each level beyond the first