In the 5e D&D player's handbook, the Dragonborn's Breath Weapon says:
The DC for this saving throw equals 8 + your Constitution modifier + your proficiency bonus. A creature takes 2d6 damage on a failed save, and half as much damage on a successful one. (pg.34)
So do I perform an attack roll against my target's armor class or do they automatically make a saving throw?
I am similarly confused about regular spells, like Lightning Bolt. Do I do an attack roll or just cast the spell?
It looks like spells bypass AC, but I don't know.