Invoke Patron Corruption Effects
I'm not going to give everything away, the results are proprietary! But here's an overview of the basics.
1-10 Your patron must be bored with you, or maybe it’s just busy. Or not listening. Or maybe it likes to see you suffer. Whatever the case, nothing happens.
11-25 Your patron is displeased that you’ve bothered it. Your request goes unanswered, but roll again and take the corruption effect.
26-40 Some pretty messed up stuff happens to you, typically involving a permanent decrease of an ability score and/or worse effects. A limb might shrivel, or part of your brain leak out your nose, or something like that.
41-85 Some other unpleasant stuff happens to you, typically with some negative aspects, such as penalties to interactions with "civilized" society (i.e. those afraid of warlock corruption), but possibly (though for sure not definitely) with some benefits as well; typically the better the higher you roll. For example, you might grow an extra eye somewhere that makes you pretty freaky looking, but that eye might have darkvision, or let you see out the back of your head.
86-99 Roll again, re-rolling anything 40 or below. You gain the corruption effect, but can remove it for as long as you retain concentration.
100 Your patron is pleased with you! You suffer no negative repercussions, and in fact you may either remove a prior corruption, or have one of your ability scores permanently increased by 1. Roll a d6: (1) Strength; (2) Dexterity; (3) Constitution; (4) Wisdom; (5) Intelligence; (6) Charisma.