Legendary Trio

The Legendary Trio, also known as Trios or Trio Dragons, are a triad of elemental dragons: Magma, Ice, and Thunder dragons respectively, released concurrently on 22nd of November, 2009. These three dragons command the three elements that they represent, and together they can Summon a Guardian of Nature.

After "The Change", they were able to breed with other breeds, including rare ones, and were then moved from the general cave to their own habitats. Each of the trio dragons is limited to one biome in which they can appear, matching their elemental design and affinity:
 * Ice Dragon → Alpine
 * Magma Dragon → Volcano
 * Thunder Dragon → Desert

Dragon Descriptions
Derived from: Ice Dragon

Ice dragons are fierce predators who hunt using their extremely cold breath. The breath of an ice dragon can freeze its prey solid in seconds. The body of an ice dragon is so cold that icicles will form along its skin no matter the outside temperature.

Derived from: Magma Dragon

Magma dragons are capable of withstanding the intense temperatures of their element. They live in volcanic regions, their bodies coated in the red hot magma which clings to their scales. They must leave the lava fields in order to hunt, requiring surprisingly little food to sustain their lumbering mass.

Derived from: Thunder Dragon

Thunder dragons are the masters of electricity. Their wings gather energy as they soar through the clouds, and when they clap their wings together they can create devastating arcs of lightning. They can stay airborne nearly indefinitely, landing only to sleep and breed; they catch their prey from the air and take moisture from the clouds. A Thunder dragon's roar is considered to be an omen of misfortune.

Breed Specific Action
As a part of the "Mod Mayhem" release on April 1st, 2010, the members of the legendary trio were given the breed specific action known as Summon, which joins their forces to summon a Guardian of Nature. The summoning is not guaranteed, but increases with each set of trios held by the user.

Trivia

 * The legendary trio were coined by TJ09, who first hinted at their relevance to the legendary bird trio in Pokémon; Articuno (Ice), Zapdos (Electric) and Moltres (Fire). The dragon that the trio summon is a reference to Lugia, based on the lore in the second Pokemon movie where the trio together command the "power of one"; an ultimate being called Lugia.
 * Trio dragons were not commonly seen during their release, which hinted to their eventual rarity. They could also not breed with other dragons, a trait shared with many rare species.
 * Both Ice and Thunder eggs have a regular cracking sequence, but Magma egg have their own unique sequence. As magma eggs mature, it looks as though magma is leaking out of the shell.