Spell-like ability Transformation Technique is a bloodline inheritance magic that all Giant Dragons possess. The Silver Dragon might acquire this magic from the Juvenile Dragon stage, whereas the Black Dragon gets delayed until the Adult Dragon stage.
Nonetheless, all Giant Dragons will obtain this ability.
Because it's a form of protection for the Giant Dragons.
The Transformation Technique truly reconstructs the Dragon Body and actively conceals one's aura. Unless one has Mastery of Soul, it's hard to recognize that the transformed life form is a Giant Dragon. This ability not only allows Giant Dragons to hide their enormous size but also makes them less conspicuous, thus preserving their dragon lives.
Many times, a large size is also a huge target.
This ability is definitely more needed by the Demon Dragon born in the Abyss, an extremely harsh environment, because there are too many formidable life forms in the Abyss that can threaten the Demon Dragon.
