It is a good idea to try and create a system of resurrection independent of the void universe as it will grant them the ability to resurrect like Origin gods without being Origin gods and they won't lose this ability if the void universe is destroyed. But Legion-7 himself who is to be the foundation of this system is vulnerable.
If he is to try to eliminate Legion-7's weakness then it will take a lot more of his divine ability slots which will disrupt his plan for the other clones. Hence why Legion-5 is not sure they should do it.
Legion-7 made his point. "I don't think we have to think much about it because it will benefit all of Legion and eliminate a very important weakness. After all, if you are unkillable that means I am unkillable. And if I am unkillable then we are all unkillable. If we are all unkillable, then whatever doesn't kill us will only make us stronger."
"That is true. But are we even sure that you can do it?" Legion-5 asked as he moved to take what he exchanged for.
He opened the door of the portal room to find a large crystal within it. The crystal is round and blue. It has a rough jagged surface so it looks more like a rock. If not for the fact that it is transparent then it would be considered a crystal.
Because it is transparent, Legion-5 could see that there are faint white streaks of energy within it that branch out like roots and flicker rhythmically. If the white roots of the crystal are considered blood vessels then the flickering can be considered the pulsing of blood as it is pumped.
Legion-5 carried the crystal out with both of his hands. The crystal was that heavy. It is about 10 meters tall and very heavy. He had to use both his arms.
Legion-7 observed, "It is beautiful and powerful. What a wonder it is."
Legion-5 grunted. "And heavy."
"It is the source of dragon Supremacy so it should be heavy."
"And now it shall be ours."
They laughed about the prospect.
"It wouldn't even be the only one. It is just the first step towards greatness."
"Many more will fall and serve as nutrition to our obsession."
The crystal is bigger than him in his normal state but he is more than strong enough to carry it. Even so, he still treated it with care. This is because, despite how powerful it is, the heart of a dragon is fragile. So he used both of his hands to carry it back to the central room. It is the most secure location in the whole base.
Legion-5 said. "Witt this we will gain some immunity to lightning. Legion is counting on you for the first step of unity. It will be a waste if you fail."
Legion-7 promised. "I won't fail as long as you are unkillable. We should be able to match Legion-8 if we work together."
Legion-5 placed the blue crystal heart on the ground gently. He tapped it lightly. It made a sound like that of thunder. Legion-5 winced at the sound.
"Lightning is truly violent. This is not going to be easy to assimilate."
Legion-7 commented dryly. "I expect this to be very painful for you. It is not going to be easy at all."
Legion-5 sighed. "I guess there is no use delaying."
Then he began to assimilate the dragon heart. His form collapsed into a blob of whitish fluid. He spread his fluid form all over the blue crystal and engulfed it. Then his form reverted to his humanoid form. He has shrunk and the dragon heart shrunk with him.
Legion-7 observed, "That didn't seem so difficult."
Legion-5 shook his head. "It is just the beginning."
He felt the heart buckle within him just as he said that. It made him stumble. The dragon that the heart belongs to is dead so the heart is not the one resisting the assimilation. The resistance comes from his existence needing to shift to accommodate such a powerful and foreign object.
After all, as a post-origin dragon heart, it must have come from dragon that was a titan of law or Sovereign of law. It is has made it extremely tasking for his existence to shift to try and match the requirements of the dragon heart.
It took a while to stabilize himself. But he couldn't remain standing. He had to sit because of the fatigue. He felt as if he was suffocating, burning, drowning, and tired from lifting a mountain all at the same time.
He said to Legion-7. "I feel so sleepy."
"Don't worry. I'll be here to protect you."
Legion-5 slept off at that point. He couldn't maintain the awareness of his consciousness anymore. It is a common occurrence for Supreme Beasts when they are assimilating divine abilities. He is stronger than his peers but he is absorbing two divine abilities at the same time so sleep cannot be evaded.
In fact, assimilating Legion-7 is more than enough for him to sleep. Legion-7 alone is more tasking than absorbing 10 divine abilities at once. After all, Legion-7 has his consciousness intact while seeds of powers are dead things.
If not for the fact that Legion-7 is not resisting then he would never be able to assimilate Legion-7. It is more likely for him to be assimilated if the two of them were enemies. This is because Legion-7 is more experienced in eating and assimilating others.
Things went without a hitch despite the weird changes that Legion-5 went through during the assimilation process. His existence didn't break down due to Legion-7 like the poor boy who was possessed. But his existence had to make a lot of changes for Legion-7 and the dragon heart.
So it was perfectly normal that his body expanded and became horrifically mutated during the assimilation. He grew several arms, legs, and many tentacles. Those are due to Legion-7. But even those changes were not as weird as the effect the dragon heart had on him.