Crimson Cascade

You unleash a torrent of blood magic that arcs from a primary target to additional creatures, dealing necrotic damage. Choose a point you can see within range. A surge of crimson energy erupts in a 20-foot radius sphere centered on that point. All creatures in the area must make a Dexterity saving throw, taking 6d8 necrotic damage on a failed save or half as much on a success.

After the initial burst, the spell sends crimson tendrils lashing out to up to 3 additional creatures within 30 feet of the original area. Each of these secondary targets must make a Dexterity saving throw, taking 4d8 necrotic damage on a failed save or half as much on a success.

Empowered by Blood:

You can sacrifice hit points (up to 15) when casting this spell. For every 5 hit points sacrificed, the initial burst radius increases by 5 feet, and the damage to both the primary and secondary targets increases by 1d8 (to a maximum of 8d8 and 6d8, respectively).

At Higher Levels:

When you cast this spell using a spell slot of 4th level or higher, the damage to both the initial burst and secondary targets increases by 1d8 for each slot level above 3rd.