The strength of the hero remains and who from it scales.

[AKUTO123]

Here the attack that destroys the mountains is carried out by the remains of the hero .
Here we see 3 mountains disappearing. Hero's relic that made this attack is nothing too special. as a matter of fact, another hero's remains survived this without any damage.
The only person that is currently equivalent to the Hero's remains is the Alpha stigma awakening ryner.

 

[AKUTO123]

I haven't been able to calculate it yet, but I think 8C will be a good level for creatures and characters that can destroy mountains. 8C is suitable for the value of destroying a mountain without computation as far as I have seen another crt

 

[Zaratthustra]

Ryner's profile is made using the light novel, not the anime feats. In the light novel is never said how many things are destroyed. It just says it destroyed the trees, or kill people.

Another thing to note is that his firepower is not compared with the power of relics. He has hax not attack power. He can destroy an army that has more than 1 million people but it's done through hax and not firepower (EE or Disintegration).

Rule Fragments don't scale between them or other users because each has its power/ability.

In the anime, the attacks show how much damage is done to the environments but in LN is never said anything about the damage cause making it a big difference.