Bloodstone

Requires attunement This red gemstone glows.
When you cast a spell that deals damage, you may
spend hit points to improve damage
You spend 1 hit point to increase the damage of
your spell by 1
You spend 3 hit points to increase the damage of
your spell by 1d4
You spend 6 hit points to increase the damage of
your spell by 1d8
You spend 9 hit points to increase the damage of
your spell by 2d6