Player.addRandomEffect

const effects = [MobEffect.jump, MobEffect.blindness, MobEffect.regeneration, MobEffect.nightVision];
const minDur = 10;
const maxDur = 9999;

//CONFIGURATION FOR RANDOM EFFECTS ^^^^^^

Player.addRandomEffect = function() {
    const randomDuration = Math.floor(Math.random() * (maxDur - minDur + 1)) + minDur;
    const randomEffect = effects.getRandomElement();
    Entity.addEffect(getPlayerEnt(), randomEffect, randomDuration*20, 3);
}