Apocalypse: I Have a System That Can Convert Energy

An apocalyptic story with cultivation techniques. Natural disasters strike in the early stages, along with mutated lizardmen and rampaging mutant beasts, followed by all kinds of catastrophes and creatures from other dimensions. The protagonist survives with the help of an energy-conversion System. The story isn't tense; it's laid-back and low-key. The protagonist feels completely secure and is also invincible. No melodrama! I'm not great at writing blurbs, so enter at your own risk.