This event introduces 6 brand-new Dragons into Dragon City.
While 5 of of the Dragons are Legendary & Category 5, one would be a Heroic (Category 11 is implied).

Either you'd have to obtain 10 Decorations to get the first 5, or you have to collect 100 Orbs to summon them. The last one would be a part of a Heroic Race.

Dragon Breakdown
-(Legendary 5) Ancient Beauty Dragon (Beauty/Nature/Light)
-(Legendary 5) Ancient Magic Dragon (Magic/Terra/Metal)
-(Legendary 5) Ancient Chaos Dragon(Chaos/Flame/Dark)
-(Legendary 5) Ancient Happy Dragon (Happy/Electric/War)
-(Legendary 5) Ancient Dream Dragon(Dream/Sea/Ice)
-(Heroic 11) Ancient Soul Dragon (Soul/Legend/Pure/Primal)