Tongue of Infernus

You swallow the silver dust, feeling your tongue be imbued with infernal power. For the duration of this spell, you have advantage on all Charisma checks. In addition, the next time you cast an enchantment spell meant to charm or frighten a creature while this spell is active, you add your Charisma modifier to your spell save DC for that spell. The level of the enchantment spell must be equal to or less than the level at which you cast this spell. After this bonus is applied, this spell ends.