|“Now you must use it to create the Fusion Dragon. Only a Fusion Dragon can punch the depths of the Boiling Sea, and only the Dragon Blade can create one.”|
“You will make the impossible possible, and unify the Elemental Powers of Fire and Water.“
“The Fusion Dragon.”
|— Ray and Maya to Kai and Nya in "Out of the Fire and Into the Boiling Sea"|
Kai and Nya created the Fusion Dragon to traverse through the Boiling Sea. Later, when Kai and Nya needed to escape the Boiling Sea, they summoned the Dragon again.
To help aid in the battle, Kai and Nya used the Fusion Dragon. However, Nya jumped off to retrieve the Reversal Blade. Without her, the Dragon disappeared. It reappeared once they reversed time, and Kai, Nya, and Wu follow the Time Twins into the vortex.
Symbolizing the unity of Fire and Water, the two-headed Elemental Dragon of Fusion is the only creature powerful enough to withstand the fierce environment of the Boiling Sea. It can be summoned only by the Dragon Dagger and is so strong-willed and powerful that it must be ridden by the Elemental Masters of Fire and Water – only when both Masters mount it can it be controlled. Ray and Maya were the first to ride the Fusion Dragon, using it to plunge to the depths of the Boiling Sea to hide the Reversal Blade, and later Kai and Nya followed in their parents’ footsteps to retrieve that Time Blade to save Master Wu.
- This is the second Elemental Combination Dragon, the first being the Hydroelectric Dragon.
- This is the second Fusion Dragon to come in a set after the Ultra Dragon, though it could be considered the third if one argues 70602 Jay's Elemental Dragon is meant to portray the Elemental Water-Lightning Dragon more than the Elemental Lightning Dragon.
- The Dragon Blade is needed to create the dragon because unlike water and electricity (the Hydroelectric Dragon), water and fire do not combine naturally.