Evil Ritual Requirements: Advice For a DM

[Fyermind]

I'd like to build an extended campaign out of a summoning ritual. Details spoilered because they probably don't matter for what I'm asking.
A Binder/urPriest/Apostle of Naberius (custom-divine-binding-prc)
Apostle of Naberius
Entry requirements:
Must worship Naberius as a deity, as an elder evil
Must be able to bind Naberius at binder level 3
Feats: Iron will, Favored Vestige (Naberius), Dark Speech
Capable of casting 2nd level divine spells
Pact Augmentation (2 abilities)
Skills: Knowledge (The planes) 9 ranks, Knowledge (religion) 6 ranks, Bluff 6 ranks, Profession (any) 6 ranks

Apostle of Naberius: d8 HD
Level BAB Saves Special Spellcasting
1 +0 2/0/2 Jealous Vestige, +1 level of existing Divine Spellcasting Class
Corrupting Speech
2 +1 3/0/3 Dark Words of Persuasion +1 level of existing Divine Spellcasting Class
3 +1 3/1/3 Dark Thoughts +1 level of existing Divine Spellcasting Class
4 +2 4/1/4 Versatile Face +1 level of existing Divine Spellcasting Class
5 +2 4/1/4 Dark Magic of Naberius +1 level of existing Divine Spellcasting Class
Class Skills (4 + int per level): Bluff, Concentration, Craft, Decipher Script, Diplomacy, Gather Information, Intimidate, Knowledge (Arcana), Knowledge (History), Knowledge (Religion), Knowledge (The planes), Profession, Sense Motive

Spellcasting: At each level of Apostle of Naberius you gain spellcasting of a divine class in which you are capable of casting second level divine spells. If more than one class meets these requirements you must choose one.

Jealous Vestige: You may bind no vestige other than Naberius. You may keep Naberius Bound indefinitely. Your Apostle of Naberius level stacks with your Binder level to determine abilities granted by Naberius and the strength and DC of those abilities.

Corrupting Speech: add your full Apostle of Naberius level to save DCs for Dark Speech, any abilities that list Dark Speech as a prerequisite, and Persuasive Words.

Dark Words of Persuasion: When you use Persuasive Words you may target all creatures within 30'.

Dark Thoughts: Any attempt to read your thoughts fails unless the reader can speak in Dark Speech. Furthermore any divination attempt made against you by one without the feat Dark Speech causes 1d6 points of Charisma damage to the caster per round. Charms and compulsions made against you automatically fail, though you may choose to have them appear to have succeeded. Any attempt to control your actions through possession similarly fails, and the possessor takes 1d6 points of charisma damage.

Versatile Face: You may use alter self at will as a standard action.

Dark Magic of Naberius: You may add the [evil] description to all spells you cast. All enchantments and corrupt spells you cast are quickened without increasing the spell level. Add Charm monster (level 4), Dominate Monster (level 8), and Mind Rape (level 9) to your spell list and spells known (if applicable).
BBEG who really likes Naberius for powering all his corrupt magic and dark speech wants to summon him and bind the entire Naberius to him. This act will result in end-times like effects from the deities, and a growing tear in the material plane if gets that far. Naberius wants back in, so he is helping, but has no intentions of being bound once he arrives, and is preparing for an epic battle. The BBEG (Balavar) has a fairly good sized following of Binders, Warlocks, Wizards, Sorcerers, Urpriests, Crusaders, Monks (by which I mean unarmed swordsages), spellthieves, rogues, and rangers. He also has a few Ur-priests, and several possessor devils and their victims.

I am looking for about ten different things he should need to perform the ritual before it happens, and another five things the players might need to do to stitch up the material plane if it comes to that.

So far I have:
1. The ritual must happen at a specific time in a specific place when the planes align properly. This place happens to be about 60' below a bustling village at noon on market day. When Naberius arrives he will be big, as in over 60' tall.

2. He will need to create a large custom magic item to channel spells of his minions and bridge the gap. To create this he needs a lot of free xp in the form of souls, dark craft points, and liquid pain. He will get this by setting up a torture chamber and abducting many innocents.

3. He needs large quantities of a specific plant that only exists in a jungle where it is guarded by fey lords of questionable morality.

4. He needs a diamond worth 10,000 gp that has never been subject to magic.

5. He needs have five seals, one for Naberius, the other four for Naberus, Kaberon, Cerbere, and Serberius

6. He must sacrifice a crane, a dog, a wolf, and 10 humans and use their blood mixed with the paste of the jungle plant, and dust from a diamond worth 10,000 gp that has never been subject to magic to draw the seals.

7. A three headed hell hound must devour three living sacrifices over the center seal at the final moment.

No idea is too ridiculous or dark, but not all ideas will be adopted. For reference, the adventure should span levels 3/4-13/15 with additional levels if they need to stitch up the plane. These challenges should be things he mostly delegates to minions who don't know what he's doing and think it is their own idea, and needn't have direct connections to PCs. The BBEG needs to be busy doing something important during this whole process so that he can't just go after the PCs when they become a nuisance. I am also looking for that important thing.

[rweird]

Idea: Have the seventh son of the seventh son of the seventh son of the seventh son of the seventh son of the seventh son of the seventh son of a creature native to the seventh layer of the Seven Mounting Heavens of Celestia (See the pattern) speak the last seven words of the ritual willingly and sacrifice his soul to fuel the gate. Feel free to change it to the nine hells of Baator or somewhere for a plane you invented. This may be to hard, though by this time, the person you're looking for might be a 1st level Aasimar warrior from the monsters manual, the problem would be finding him, though it also could be a Solar. Take it or leave it, just an idea, may be a bit to high level.

[jackattack]

BBEG needs to endure several ordeals before the event, either individually or together.

He has to fast for a week. He has to be silent for a month. He has to meditate in complete isolation for a month. He has to remain in a magic circle on top of a mountain while hopping on his left foot for twenty-four hours. He has to wear a burning medallion next to his skin for six weeks.

Anything that can be interrupted and/or takes his attention away from the party will work. Interrupting the ordeals might not blow the ritual, but it might reduce his chances to succeed, or force him to do something else quickly to compensate (and give the party some breathing room).

[JoshuaZ]

Useful dark ritual ingredients or aspects. Some of these are substantially easier to get than others.

1. Blood from someone of royal descent. Depending on context and evilness, may require their sacrifice as part of the ritual.
2. The cooperation of multiple spellcasters who use distinct forms of magic. Maybe you need a warlock, a wizard and a cleric for example.
3. Dust from the grave of someone who died trying to stop the same ritual previously (how did the ritual ever get attempted in the first place? Time-Whimey Ball!)
4. The sacrifice of a fallen paladin.
5. Dirt from the grave of an unjustly executed person.
6. A rope used to hang someone.
7. Ashes from a dryad's tree that was burned.
8. A tooth from a child.
9. Deadly nightshade picked at a new moon.
10. The text of a prophecy that never came to pass.
11. A dagger with specially carved runes on it. The dagger is itself non-magical, but it is needed for the ritual.
12. An obsidian statue, carved in great detail by someone who does not know the purpose of the statue.
13. A small agate soaked in the blood of a druid slain for just this purpose.
14. Chips of bark from a willow tree, soaked in a mixture of unholy water and silver dust.
15. The heart of a child killed by their own mother.
16. A wooden stake used to mistakenly slay someone who was thought to be a vampire.
17. A pauper's last coin.
18. The body of a sailor who died at sea.
19. The first stone set down in the building of a now destroyed castle or fortress.
20. The ashes from the burnt remnants of what was the last copy of a book.
21. A diamond that has never been exposed to sunlight nor the target of any magic spell.
21. The body of someone who has died exactly three times.
22. A holy symbol cracked in half by someone who was a cleric of the faith corresponding to the symbol who has rejected their faith.
23. The last air breathed by an archmage right before their death.

Since the ritual does involve binding, it could also connect to that in some way. The following suggestions connect to that:
24. The Tooth of Dahlver-Nar corresponding to Naberius.
25. The body of someone whose mother bound Naberius while pregnant with them.
26. A piece of human skin with Naberius's seal carved into it while the person was alive.
27. Implements of binding.
28. The seal of a vestige which no one has bound before. If that's too ridiculously hard consider instead:
29. The seal of a vestige which no one has bound for at least a hundred years.