Source Touched

You have been touched by ancient magic that allows you to enhance your attacks once per turn with certain kinds of spells, you can choose to gain one of the following benefits:

• When you cast a spell that requires you to make an attack roll, double your Charisma modifier as it applies to the Attack.
• When you cast a spell that requires the target to make a Save, double your Charisma modifier as it applies to the DC.
• When you cast a spell that deals damage, you can choose to add 1d4 of Lightning or Thunder damage on top of the damage roll. This damage ignores Resistances and  Immunities.