DC 15: Snow dragons live in cold places, their breath weapon is a blast of frost.
DC 20: Snow dragons are easy to bribe with gifts of diamonds, easier if the gift includes meat. Young snow dragons that embrace their penguin cult become fat bloated creatures that resemble toads more than lizards and lose their ability to fly more than a minute or two, some lose the ability completely.
Snow Dragons are on pages 84-85 of the Monster Manual
Mourningstar Campaign