Even if the Archlich did get the 'Undead' keyword, I think DM adjudication would prevent this from happening. Vecna is the god of undeath; if he wants to exclude you from his aura, you better believe you're going to be excluded from his aura.
While I am aware of this forum's stance against calling out on houserules, it is statements like this (amongst others made later on) which really irritate me. It has always bugged me the wrong way ever since I joined this forum, and to this day, it still continues to do so unabated. You are going to have to forgive me here, it is like some fishbone stuck in my throat which I simply have to spit out.
So you have a character build which just happens to work particularly well against a particular foe. Whoopee-de-do. Simply because that foe so happens to be a god (and lord forbid that a party should have a reasonable chance of fighting a deity, even when level comparisons might indicate otherwise), and because it apparently offends the sensibilities of some that
a character optimized to fight a certain enemy should fare quite well against it, they evidently see the need to start calling in all sorts of ad-hoc rules as to why this would not work. So he can now exclude PCs from his aura. Why don't you just say that his aura can now automatically punch right through necrotic resistance? Or banishes you to another realm with a flick of his finger without getting to roll for defenses or saves?
Misunderstandings of the rules, I fully support (such as Vecna voluntarily lowering his aura if he feels it may be benefiting the archlich more than it harms), or the fact that an archlich is not an undead.
But being punished simply for being good at what I do? (Such as that statement about you becoming the new Vecna, being relegated to the equivalent of an NPC and henceforth removed from the game). Absolute nonsense IMO. I believe that whether a party prevails or falls in a fight with a foe should really just depend on their stats and tactics. Otherwise, you may as well just eschew all stats and let combat be decided by who can do the best job of trash-talking everyone else.
In fact, if the PC in question was able to access some means of actually being healed by Vecna's aura, I see no reason whatsoever to deny him that. Vecna was given stats for a reason, to delineate the boundaries of his power and let the DM know how he is expected to fare against a party of a certain level. I don't see the need to accord Vecna any special DM-protection status simply because he is a god. If he does fall, it is just because the party is stronger than him. In that case, he deserves to go.
You say any reasonable DM would change this or that to screw around with the archlich? I say a reasonable DM should accord the archlich all the full benefits (if any) he is entitled to when facing Vecna. Or any other foe where his special abilities may come into play. And not suddenly spring this sort of stunt on the player in question.
Ah...feel so much better now that it is off my chest...
