Mark of Infernal Resistance

While the blood of fiends runs through the veins of all Tieflings, the mana pathways of a rare few are further empowered by the strength of their unholy lineage. This unlocks greater resistance to the aggressive forces of the outer planes, as possessed by some fiends. You gain the following benefits:

• Increase your Constitution score by 1, to a maximum of 20.
• You have resistance to acid damage, lightning damage, and necrotic damage.
• You have advantage on saving throws against being stunned.