In any city, in any country, go to any wedding you can get yourself into. Walk up to the stage and ask the organ player to see someone called "The Holder of Slaughter." Should he give you a sly grin, you have come to the right place. With a wink, he will pass a machete to you from under the keys, and tell you to lock the doors. Stride purposefully to every door and make sure they will not open, and do not worry that anyone will see the weapon. Tap the hilt of the blade to every locked door and every window; this will ensure that no one escapes.
When you have done so, move to the farthest row of pews and stand in the aisle until the organ player strikes up a mournful, haunting melody, much to the confusion of the assembled well-wishers. Wait for exactly twenty-nine measures to pass. When the thirtieth measure begins, lift the machete over your head and strike the first person who is within your reach.
Amid the terrified screams, the music should become louder, ringing through the pipes with force enough to shake the entire church to the foundation. Now, you must, with great leisure and deliberation, move back and forth along the pews, slashing at every occupant of the building. You must show no mercy, no hesitation, only a slight bemusement at seeing the floors, and your body, washed in innocent blood. If you allow even the smallest hint of mercy to enter your mind, the forces in the blade will consume your soul, torturing it with endless guilt and agony, while your body becomes their tool.
As you sweep along the rows, you may hear the preacher continuing to speak, highlighting all of the best deeds of humanity and citing many things you and your family have done; listen not to his sermon, for he knows this game well, and is trying to confuse you into pausing. When the rows are clear, kill anyone standing at the doors, and watch them scramble to the main aisle, gathering in front of the podium. Flames will leap from the keys of the ancient instrument as you methodically walk towards them, outlining the few remaining survivors. Give them your maddest grin and tell them, soothingly, "Only the tainted fear death."
Lash out and cleave the groom's head in two; killing anyone else with this blow will alert Heavenly powers to your presence. The man's head will explode, but the body will turn and leap to the preacher. Spikes of bone will erupt from the corpse, severing many of the elderly man's arteries; now, you may finish off the rest of the guests, but save the bride for last.
She will fall to the ground, weeping uncontrollably; kneel down to her and pull her head to face your gaze. Kiss her on the forehead, and ask her where God is. If she begins to laugh, then He is here, and will exact a punishment that will rival all the pains of the Old Testament. Should she cry harder, wailing with grief, then pull her gently to a stand and embrace her. The organ player will now rise, a corona of fire wreathing his body, allowing the instrument to play itself, and walk down the stairs to you with an outstretched hand. Give him the machete, and do your best not to feel any regret.
Flames will surround the weapon, and he will ram it through both of you; the bride will be in too much pain to scream as both of your bodies are burned to ash. If you have any remorse at all for what you have done, then this pain will only be the beginning of your eons-long torture. If you have none, then it will feel as if the fire has permeated your very soul, obscuring your vision with a red haze. Then, like a wisp of smoke, they will be gone, and you will see the church again, only now, it is an effigy of hell.
The walls are now crafted of flesh, oozing blood and pus from countless gaping wounds, fire sprouts up from the floor with no warning, and the air is heavy with the cries of thousands of tortured dead. All of the revelers are chained to crudely formed pews of bone, impaled in every joint by nigh-molten skewers of steel. The bride will be before the podium, her limbs spread wide as she is secured to a rack-like device. Clusters of grotesque, malformed demons will peruse the crowd, randomly grouping together and ravishing the helpless souls, staining them with gouts of saliva, semen, and blood.
And in all of this, you must stand and watch, unfazed. Even wincing once at the various activities will cause the demons to mistake you for one of the guests, and subject you to the same treatment. After a handful of eternities, the demons will all converge on the bride, pleasing themselves in fashions that no ordinary human would be possible to achieve. Chunks of flesh, human and demonic, will fly through the air while they rape the woman's soul. When all of them seem to stop, take four steps down the aisle; they will all disperse, leaving her covered in more fluids that you will be able to identify. The organ player will appear before you, saying that you have preformed a unique and kind service for him, and state that he will give you one concession for your deeds. Ask him in an even voice, "Why do they kill?"
He will look at you, clearly confused for a moment; ask him again, and he will break into a kind, fatherly smile, and explain, in a voice that is neither human nor demon, the multitude of reasons they have for seeing so many dead. Visions of great atrocities will swim in your mind as he speaks, picturing every one with you as their instigator; this may drive you mad, but if you are truly set in this path, you will see them as only a minor annoyance. When he has finished, he will tell you it's time to go, and touch you on the shoulder; the pain of immolation will strike you again, and everything will go dark.
You will wake up the next day in the place you call home, with the morning's newspaper beside you. Its headline will shout of the mysterious murders of an entire wedding party, with no suspects to be had; beside the paper, there will be a thank-you note with a signet ring attached.
This is Object 93 of 538, the Seal of Eternal Genocide. Your path is set, for you are now beyond redemption.