The Father of Lies
Assassin
STR E ~ B
EN E ~ B
AGI E ~ B
MA A+
LU EClass skills:
Presence Concealment B
The skill of concealing one's presence. At this rank, the user is concealed from the senses of even most Heroic Spirits, though an attempt to attack drops the rank.
Combined with Shape-shifting, the Servant is almost unsurpassable at making infiltration.
Personal skills:
Shape-shifting B-
Since the human form is just a shell around his true essence, Assassin can freely change his shape and internal workings to whatever he desires.
In effect, this gives him a pool of stats he can distribute at will to either his Strength, Agility or Endurance, and rearrange when and how he wishes. His Magic and Luck stats cannot be changed, however.
The shape-shifting has another flaw: every form he takes must have some small but noticeable nod to his true nature.
Whether it's goat hooves, horns or some physical deficiency like a hunched back, they're apparent to anyone who looks hard enough.
Nature of the Rebellious Spirit A
While a distinct entity from both Lucifer, the greatest of the fallen angels, also known as Helel, and Satan, which was the entity that was responsible for judging souls, the Devil is still rebelling against the Christian God by corrupting and tempting mortals.
This skill negates the effects of Charisma of any rank.
Divinity A++
Recognized as the embodiment of if not evil, then at least temptation the world over, the Devil is a fully divine entity.
However, to be able to manifest in a Grail War, only the aspect of him that tempts Man by taking their form can be summoned, heavily restricting his power.
Noble Phantasm:
Mephistopheles ~ A Deal With The Devil, A Pact Signed in Blood ~ E
A Noble Phantasm, formed by tale upon tale of trickery and deceit, taking the form of a contract.
While its shape is as fluid as that of its owner and changes based on the intended recipient, certain facts are immutable: it takes the form of some sort of writing implement like a pen, which is always paired with something to write on - usually the contract is written on plain paper, which only requires the target to sign to complete. It contains no small letters, or other attempts at deceit: the terms are spelled out clearly, concisely, and in the language of the speaker.
The terms always amount to the same thing: in return for their soul, Assassin will do everything in his power to make a single wish true, which has been spelled out beforehand. However, Assassin is not inclined to take on wishes he cannot fulfill, and will lash out if the contract holder attempts to break the rules of the deal.
After the victim - for that is what the signatories are - has signed the contract, Assassin will grant the wish, before taking their soul.
With souls in his possession, Assassin can consume them for large amounts of mana, enough to let him survive a day without a Master per soul, use them to take fatal blows in his place, or summon biblical demons into the world, equal to a Servant with every parameter at rank C.
The effective capacity of the bag in which he stores these souls is infinite.
Notes:
Now before you go off on me for breaking a fundamental rule of HGWs and letting Divine Spirits be summoned, this is only an aspect of the Devil, the aspect of him appearing on Earth to trick mortals into signing away their souls to him.
Hence why he's only got one Noble Phantasm and not the absolute shitload he'd have when summoned as a full Divine Spirit.
Anyway. Original title of the NP was, you might guess, The Devil Went Down To Georgia.