Anyone know any chant or darks on the mysterious being called the Serpent that sometimes aids Vecna? Any guesses as to who the Serpent might be (my money is on Asmodeus... if Vecna's plan to take over Sigil had succeeded, no doubt his "ally" would have shown up to claim the prize!)
Vecna and the Serpent
Whether Vecna is insane or not is a subject of some debate.
"Genius and Insanity are separated only by success" - Tomorrow Never Dies
Few are as successful as Vecna.
Powerful Mage
Lich
DemiGod
Escaped Ravenloft as a Darkord
Invaded Sigil
Intermediate Power
In the Ravenloft module Vecna Reborn the serpent, and Vecna's relationship with it, is defined thus: "Some mortals manipulate the tiniest bit of the Serpent and call themself wizards and sorcerors but the Serpent speaks directly to Vecna" - Monte Cook.
I personally see the serpent as one of the brothers or sisters (or even one of) the serpents responsible for forming the planes from the primordial chaos that was the universe.
I think what he's saying is that all mages interact with the Serpent in some way - that this is what magic is. "The Serpent speaks directly to Vecna" is another way of saying that Vecna is a very, very proficient mage - this shows the level of magnitude his magic-shaping is above your typical dweomercrafter.
Here's how the Serpent is described in The Book of Eldritch Might II:
"The power of eldritch might stirs in the heart of the multiverse with an intelligence and a soul all its own. The most powerful arcanists know this and grow familiar with magic’s own mind and spirit. Some call it the Serpent, and others call it the Godmind or the Soulspark.Whatever they term it, they know it exists—even if they never speak that knowledge aloud." - Monte Cook
Here's The Epic Level Handbook:
"Are you ready?
You’ve heard about spells that transcend the commonly understood arts, scribed in the margins of ancient tomes and whispered, among the acolytes of mageguilds. In various times and places, epic spells have been personified as “the Serpent,” codified as True Dweomers, and encoded as part of an ancient lore called the Language Primeval. Whether epic spells really are straight from the Serpent’s maddening whispers or are revealed to you over countless curious volumes of hidden lore, you are ready to grasp the ultimate level of mortal magic." - Bruce Cordell (probably)
Strikes me as a metaphor. The Serpent is magic, and the Serpent's "whispers" are powerful arcane secrets. But, what we must remember is that belief shapes the planes. So, if people believe there is a mystical magic serpent out there that controls (or possibly is) all magic in the Multiverse, then such a thing must exist. If and how Vecna learned to speak with it is another question entirely, but, I mean, he's the Lord of Secrets and formerly the most powerful mortal mage in existence. If anyone would know how to speak with the Serpent, it would be him.
The Serpent is defined in the Epic Level Handbook and The Book of Eldritch Might II as magic itself, basically one way of looking at epic magic, at the words of power that make it up.
The Serpent is probably not intelligent in any way that mortals or immortals would understand. Vecna is just crazy. When the Serpent speaks to him, Vecna is really talking to himself.