Duergar Magic

When the creature reaches 3rd level it can cast the enlarge/reduce spell on itself once with this trait, using only the spell’s enlarge option. When it reaches 5th level, it can cast the invisibility spell on itself once with this trait. It doesn’t need material components for either spell, and it can’t cast them while it’s in direct sunlight, although sunlight has no effect on them once cast. It regains the ability to cast these spells with this trait when it finishes a long rest. Intelligence is its’s spellcasting ability for these spells. (Duergar, pp. 104, SCAG)