Create Weakness

All creatures of your choice within your range must succeed a constitution saving throw or be vulnerable to one damage type of your choice until the end of your next turn.

On failure, immunity to the chosen damage type will be treated as resistance, resistance will be ignored, and regular damage will be treated as vulnerability.

A creature can only be affected by one casting of this spell at a time. 

For each Spell level above the 3rd, you may choose an additional damage type to add to your casting, up to a maximum of 3.