The world is full of monsters that can easily destroy the entire planet, this world, no universe is radiated with immense mana that is being spread by planets that recycles it and launches it into space to connect with other planets.
Thus every planet in the solar system connects to each other, so destruction on a planetary scale made by the lifeforms living in them, will be lowered to that of a village.
No matter how powerful one becomes, along one is birthed from worlds, their true power will be lowered by the planets and deem the source as a threat and send its body to the past where creation and time has not begun.
The planets deemed it as punishment.
That means with the planets mana covering them, with a wide destruction really capable of sweeping the entire solar system, instead of lowering it, other planets directed the attack to other solar systems or took its attack.
Of course not all planets are as outrageous, other planets evolve in other ways like making the lifeforms live in its plane to mature and allow it to transcend to reach the level of other planets.
After all the source where these planets began to transform and protect itself is made by magicians who almost turned the entire planet into a large array of spells.
Some planets don't have mana, but the people born and reached the high of the skies gave it mana to survive wars across the galaxies.
So whenever a war happens or a casual attack and a planet would be caught up in it. If the planet cannot diminish the mana upcoming to it, it would die and explode from its attack and let the spells or people who transcend death rewind its state before the attack could meet it.
It was a terrifying universe where planet destroyers met their end easily or scared the breath of the planets, that's why there are guardians to these planets, so called gods that it cultivated to reach the peak of power in its own planet.
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I thought of this idea, cuz it's so cool. Imagine a fight between the strongest, the ultimate attack made by one of the ones fighting was dodge and the attack continued, until it hit a planet and cut it in half, an amazing sight happened, said destroyed planet irreversibly affected its surrounding space. Following that the planet reassembled faster to the naked eye cannot see and the planet returned like nothing happened, how cool is that.