Once he gains their trust, he can initiate an alliance with his other avatars, uniting the power in this domain, causing the two invading armies to have a much difficult time conquering this location.
He trusts Amethyst with his life, he knows that she must have discovered perfect vessels for him to control.
At least, the other powers are much easier so he just leaves it to her, the Everlasting Whale Race is known to be powerful giants but are actually gentle giants, they live just like how normal whales would, not having an ambition.
The Sea Dragon Race is easy for Amethyst to takeover, she doesn't even need to take an avatar, with both the dragon and Origin Bloodline, she can use his body to pressure them to serve her.
For the Black Turtle Dragon Race, Amethyst also does not need to create an avatar, they are cowardly and rather not want to participate in any conflict since for them, the longer they live, the stronger they become.
