Strictly speaking, more accurately, if cultivating this auxiliary magic skill can truly enhance a cultivator's aura, then it could be directly used as a combat magic skill.
For instance, when encountering cultivators of the same stage, one can directly transform into the aura of a Gold Core cultivator, suppressing the enemy with oppressive force, reducing their combat power to less than a tenth under the pressure of a higher-level aura.
As for the last - changing physical form - this is an even more advanced level than augmenting the aura.
In his conception, one could transform a cultivator's aura into the aura of the Evil Clan, or even into the aura of the Heavenly Demon and such.
This fanciful conception opened Han Yi's eyes wide.
In the Immortal Pavilion, the reason why Shangguan Yun didn't mention morphing among races was that this concept was merely from the Nascent Soul True Lord who invented this magic skill, but hadn't formed even a conception yet.