Blood Price

Casting the spell

You lash out with a sudden blood curse as a creature channels power. When a creature within range casts a spell, uses a special ability, or activates a feature, you can use your reaction to curse it. The target must make a Constitution saving throw. On a failed save, it takes 2d6 necrotic damage and becomes vulnerable to necrotic damage until the end of its next turn. On a successful save, it takes half damage and does not gain vulnerability.

Overcasting the spell

When you cast this spell, you may spend additional Vitality Points (VP), or Hit Points through your Lifeburn feature, to empower it. For each additional VP spent, the necrotic damage increases by 1d6. Overcasting does not extend the duration of the vulnerability.