Baraka's Resistance Breaker

You exploit a creature’s recent wounds to shatter its defenses, exposing it to further damage. Choose one creature within range that has taken damage since the start of your last turn. The damage types it has taken during that period are affected by this spell.

The target must make a Constitution saving throw. On a failed save, its resistances are reduced as follows until the start of your next turn:

• If the target is immune to an affected damage type, it is treated as resistant instead.
• If the target is resistant to an affected damage type, it is treated as having no resistance.
• If the target has no resistance to an affected damage type, it is treated as vulnerable to it.

Additional Effect: All damage of the affected types dealt to the target while this spell is active is considered magical.

At Higher Levels. When you cast this spell using a spell slot of 4th level or higher, you can target one additional creature for each slot level above 3rd.