So your character has decided to consume someone's soul and you would like to know what happens. Think long and hard before you decide to do this, it is not an action on a whim, the Diablary will shape and change your character, if you are caught, you most likely will be Blood Hunted and killed, and even if you are not caught right away...
Failed Diablary: You botch your last strength roll or the victim has a Willpower of 10... chances are the victim will frenzy and turn the tables on you, and that is just the good news, if you survive the frenzy, your attempt may be reported and punished by your Prince, you may find yourself chased out of town because while you did not commit the sin, you did try, or you may find yourself coming to an abrupt end, for if you did it once, you may do it again and your Prince wont like that.
Nightmares: You will receive nightmares equal to the number of nights of the target's Willpower rating. This means you will need to roll every time you wake up to see if you successfully faced down your terrors. If you fail, you will find yourself with lowered dice for the night. If you botch, you will be trapped in the nightmare for the game night. STs will roleplay out what your nightmare is, and just because you succeeded in your roll doesn't mean you wont be a bit jumpy or freaked out at things during your waking hours.
Humanity: You consume a soul, you lose a point of humanity, no roll needed, no exceptions, frenzy or choice, you eat that soul, you will lower your humanity.
Diablarizing a Malkavian: Be careful, you may find yourself with other derangments as well, they are known for their insanity and it is infectious... Your successful diablary of a Malkavian may or may not have nightmares, and may or may not have a different derangement affecting the character for the duration of game nights as equal to the victim's Willpower rating, or even permanently.
Diablarizing a Nosferatu: Be careful, even as with the potency of the Malkavian's blood for insanity, the nature of the Nosferatu's blood warps those who partake of it. To diablarize a Nosferatu may confer upon you some of their taint and curse, dependant on how much of their Vitae you have consumed. Your body may be able to fight off the change much like mortal's do infection, however it will take time, be costly and affect you, otherwise you may find you lose an appearance point, or develop some form of disfigurement, which, while not as intense as the Nosferatu curse, does mark you and depending on your ability to fight this 'infection, may eternally remind you of your sin.
Your Aura: It will be marked with the stain of Diablary, your aura will be swirled with wisps of black, and any who use Auspex on you will be able to see this and know you for what you have done. You may be lucky and only find yourself under the Blood Hunt and meeting the sun, but chances are it will be far worse then this and you will find just how horrific being blackmailed can be.
Discipline gain: Upon the successful diablary, your character will recieve a single point of the victim's highest discipline. If you already have that ability, you will recieve a dot in the next highest. If there is a tie, we will roll a dice, odds for one, evens for the other. If however, the one commiting the Diablerie all ready has all the Disciplines of the target he eats, then no Discipline is gained.
Generation gain: Gaining here differs depending on Potency of the victim and the eater. If the target is enough Generations lower, a Diablerist can gain several steps or likewise, if they are of the same generation, nothing changes. The Generation gain is indicated below:
1-2 steps below = 1 Generation step lowered.
3-4 steps below = 2 Generation steps lowered.
5-6 steps below = 3 Generation steps lowered.
If the eater has the Thin Blood Flaw, a successful diablary of a lower generation character which results in a Generation of 11 or lower, they will automatically remove this flaw.