Resistive (5e Feat)
From D&D Wiki
Prerequisites: Constitution 13 or higher
After years of having to deal with your inhospitable environment, you have gained resistance to the very thing that had made your life hell. You are now resistant to one damage type of your choice. If you were already resistant to the damage type, the damage now is reduced to 1/4. If you were originally vulnerable to the damage type, it now does normal damage.
You may take this feat multiple times but only for the same damage type. Does not stack with other feats or armor induced resistances. Damage resisted can only be reduced to 1/4.