Fiendish Legacy: Level 1
You have Resistance to Fire damage. You also know the Fire Bolt cantrip.
Fiendish Legacy: Level 3
You learn Hellish Rebuke.
Fiendish Legacy: Level 5
You learn Darkness.
Touched by the Nine Hells
The infernal legacy connects tieflings not only to Gehenna but also the Nine Hells and the raging battlefields of Acheron. Horns, spines, tails, golden eyes, and a faint odor of sulfur or smoke are common physical features of such tieflings, most of who trace their ancestry to devils.
As an Infernal, you have these special traits.
You have Resistance to Fire damage. You also know the Fire Bolt cantrip.
You learn Hellish Rebuke.
You learn Darkness.