The Phoenix Creature is a mysterious creature which emerged from one or more Xel'Naga Temples. One was observed on Bhekar Ro.
The Phoenyx Creature is a massive being of enormous destructive potential. Its internal energy form is barely contained within its luminous skin. It has giant feathery wings, grasping tentacles that protrude from its ventral surface, and glowing eyes. It is capable of space flight.
The Phoenyx Creature is a powerful telepath, capable of being sensed by Ghosts and Protoss such as Judicator Amdor. The latter believed the presence's power was greater than the combined mental power of the Protoss race.
It has the ability to emit "scanning beams" which disintegrate creatures and objects of interest. It uses the beams to absorb the genetics of Protoss and Zerg. While it is capable of absorbing Terrans, it seems to have little interest in them.
In addition, the energy creature is capable of absorbing incoming energy attacks and converting them into biological and metabolical energy.
The Temple absorbed numerous Protoss and Zerg, granting it enough information to "awake" and undergo a metamorphosis. The Temple absorbed the energy from a nuclear attack, which the creature used to combine the genetics of the Zerg and Protoss within itself to complete its maturation.
The Xel'Naga Temple of Bhekar Ro was uncovered by a violent storm. Its first act was to absorb a hapless Terran who ventured too close.
During the battle, a Ghost dropped a nuke on the Temple. This granted the temple enough power to awaken. A chrysalis exploded its way out of the Temple, hatching and releasing a Phoenyx Creature. As it flew from the battlefield, it absorbed the creatures around it and reached another stage of maturity. Excess bioenergy created from the nuke's energies caused an explosion in planetary growth due to the expelled bioenergy residue.
Xerana opined that the creature was a young hatchling and only accidentally absorbed Terrans. It "released" the ones that had been absorbed around the Temple. However, this did not prevent it from absorbing Terran fleet crew members as it flew from the planet.
The Xel'Naga Temple of Jahdir was uncovered by a violent fire storm. Its first act was to absorb a small Zerg scouting party of the Succubus Brood. The nomadic brood was only interested in assimilating Terran and Protoss entities into the rogue swarm, and speedily avoided the Temple's general area. Shortly afterwards, a massive energy shockwave occured, and may have stemmed from the Temple, and therefore, from the Phoenyx Creature within. The shockwave burned the planet's entire surface and blasted a large part of its west side into space.
A Xel'Naga Temple was present on the world of Nemaka as well. The top had been blown open, and archaeologist Jake Ramsey theorized that an energy creature hatched out of there (within the last fifteen years).
It is believed by Patriarch Darr that the "scanner beams" may work in a very similar way to the genetic light energy imprint technology of the Protoss Phase Prism. This theory is inspired by the information passed to Shakuras by the Dark Templar Xerana: that the scan-absorbed Terran were expelled as not only whole, but living entities. This gives rise to the belief that the reverse energy signature of these beams of light may in fact draw life imprinted within the conciousness of the Phoenyx Creature out and "resurrect" those that have been absorbed.