AG's Boon of Withering Acid

You have resistance to Acid damage. You learn the Vitriolic Sphere spell. You can cast this spell using spell slots if you have ones of the appropriate levels. This spell uses your spellcasting modifiers, or has a DC of 17. Additionally, you gain the following effects

• This boon has 10 charges that recharge on a long rest
• You may expend 1 charge to ignore resistance or immunity to acid damage dealt by you or creatures created by your spells or features until the start of your next turn.
• You may spend 2 charges to convert all the damage from the attacks you make or spells you cast to acid damage for the turn.  If the spell or attack already deals acid damage, you instead corrode the target’s armor, reducing their ac by 4 until the end of your next turn.
• You may expend 1 charge to cast Vitriolic Sphere using one of your spell slots as a bonus action. Alternatively, you may spend 3 charges to cast the spell as a bonus action without consuming a spell slot and ignoring the material component.