One day a guy dies in an accident and then when he woke up he finds himself in a different body and after waking up a word is branded deep inside his consciousness and it said °} ABILITY: TURN LIES INTO TRUTH {°
So basically that's the premise and in more detail about his powers:
1.) It can only happen if the lie is believed and at least a bit of believing in the lie, though if it's only believed a little, then the turned into truth is also less.
2.) It can only affect him not other things, like he can't say a lie about a rain is coming and that rain will come if believed, it can only happen if it's about him physically and spiritually, so no lying about you're rich and then you become rich. Though you can affect your experience, like saying you're a veteran soldier and if believed you'll have the experience and physical abilities of a veteran soldier, but you won't have a background of a veteran soldier it's just the experience your taking.
3.) So your ability is actually limited, like the more exaggerated the lie is, the more energy it needs to have, so if you lie about being omniscient and for some reason a lot of ordinary people believed it then you'll be omniscient a little, by little I mean 0.00000000000000000000 and so on 0 to 01%.
4.) The more powerful a person that believe in the lie, the more energy it provides to the lie becoming true.
5.) You cannot hypnotize people into believing in your lie, though you can have some bits of passive like the devil's whisper, into which it convinces the person into believing you by saying some nonsense. Now the reason for this is that this ability is primarily about deceiving the other's, so the ability you can only have, is abilities that will turn the people's belief through persuasive techniques.
So that's basically it, I just found the concept to be thrilling to read. Thank you for your attention and have a good day.