Tieflings no longer have the spurn of Asmodeus in their lineage. in Carnassus, Hyperion’s maiden, Serena, is seen as the Moon at night. occasionally on these nights where Serena’s light shines bright, she choses a specific child to bear her mark, and that child becomes Moon-Touched. These children are rare, and are viewed special by the Church.
From the PHB, for any Tiefling PC’s replace Hellish Resistance with Lunar Resistance; Infernal Legacy with Serena’s Legacy; and Languages as below.
Lunar Resistance: You have resistance to cold damage.
Serena’s Legacy: You know the thaumaturgy cantrip.
Once you reach 3rd level, you can cast the moonbeam
spell once per day as a 2nd-level spell. Once you
reach 5th level, you can also cast the darkness spell
once per day. Charisma is your spellcasting ability for
Languages: You can speak, read, and write Common and one other language.