|OPEN are the double doors of the horizon|
Your mind is deeply, permanently integrated with the fabric of the universe. You leave ripples in the world where you walk. You are more ontologically real than anyone else. The world around you is roped into your cognition. Wizards speak the language of the universe. You are a word in that language.
To wield your psionic powers, compose a sentence that has your Word in it. Roll 1d6 for each word in the sentence. If the total is less than your INT, the sentence occurs, to the letter. If the total is greater, the GM gets to change 1 of the words in the sentence (besides your word) for each die that came up 3 or greater, then the new sentence takes effect. In any case, something will happen.
Psionic effects only persist while you are within line of sight. You can only have (INT) words of effects going at any time.
Psions' words are always verbs. We are already many nouns and adjectives - MORTAL, FLESH, POTENTIAL, FATED, are but a few - for the verbs of the world to act upon. A psion is not merely an actor or acted upon. You are the action.
Your word must be the main verb of the sentence. You are the word, and you are taking action, so the word will occur. This is not a wish machine. Just because you can pull the world's levers does not mean that you know which mechanisms they control.
Psions look like everyone else. They do not feel like everyone else. Others exist, you EXIST. Even if someone doesn't know what a psion is, they will feel uneasy around you, a profound sense of irrelevancy and inconsequence. Many psions use this to gather cults, feeding on their disciples' fears of inadequacy to keep them dependent on their (usually bogus) teachings.
Psions can be of any class. Think of psionic abilities like mutations; they often come from the same sources. Ancient magics, industrial accidents, meteors falling from the stars, other psions' curses...
Psionics are not limited to the once-mortal. Aberrations stir in the depths, concepts so powerful they have instantiated themselves in flesh. When you speak or enact their words, you call to them, and so they arrive in times when their words are strongest. Aboleths, the word ENSLAVE. Illithids, the word DEVOUR. Shardminds, the word FUSE. Beholders, the word BEHOLD. Some say that gods are naught but more aberrations, ones that all share the world BELIEVE.