...freaky fish eyes!

Name: Caster, Bluebeard, Gille de Rais
Origin: Fate/zero
Gender: Male
Classification: Heroic Spirit, Servant
Age: Unknown
Powers and Abilities: Super speed, strength, summoning
Weaknesses: None
Destructive Capacity:  likely wall+-building level with average summons much higher as a lovecraftian abomination
Range: Varies
Speed: Supersonic
Durability: at least wall level 
Strength: Superhuman
Stamina: Superhuman
Standard Equipment: Prelati's Spellbook
Intelligence: Knows how to use his book
Notable Attacks/Techniques:

Prelati's Spellbook: Prelati's Spellbook is a demonic guidebook with a cover made of human skin. It allows the summoning of water demons from the depth of the seas.
It isn't just a bunch of papers with curses written on it which Caster can read: the book itself functions as a prana core which it uses freely. It isn't connected to the user's prana. It enables the use of high-level magecraft and ritual magecraft.
It doesn't actually allow direct control over the water demons it summons, but it allows the usage of a ritual magecraft class that tens of people couldn't do together, depending on the verses pronounced.
It is based on the R'lyeh text from the myth of Cthulhu. It probably was copied from the original book in R'lyeh language, translated into Chinese in the Xia dynasty from the sunken spiraled city, then translated into Italian by François Prélati. Of course it would be able to summon fantastic aquatic creatures.

Notable OBD Victories:

Notable OBD Losses:

Other: Not to be confused with the character of the same name from Fate/Stay Night or the similarly - named weapon from Outlaw Star.

Base Caster/