Undead Swarm (3.5e Optimized Character Build)

Introduction
Summary::Fill the battlefield with disposable undead! Drain the blood of your enemies! Unleash the forces of death from all directions!

Game Rule Components
This build doesn't need much; even a lot of the stuff on its table isn't strictly necessary. Mostly, this showcases how Necromantic feats work.

Items
None necessary. A Cloak of Charisma helps to make your spells harder to resist and make you less naked, though. A wand of Darkness helps you hide from the hated sun, which might be useful.

Progression A
Starting Ability Scores (Before Racial Adjustments): Cha 18 and you don't even care about the rest. Con is nice since it gives hit points and you're not going to lose it for becoming undead, but the others are irrelevant.

Race (Templates): Aasimar Vampire]]

Starting Racial Traits: Starting as an Aasimar gives +2 Cha, for a total of 20 Cha. It also gives you +2 Wis. You don't care. It also gives you Darkvision 60' and Light once per day. You don't care about that either.

Conduit of the Lower Planes 5/Vampire Paragon 3]]

Vampirized!
When Vampirized!, you get turned into a vampire. This probably happens willingly, and ideally happens in a properly desecrated temple to an evil deity so that you can get extra hit points. This gives you a further +2 Charisma, which you care about (it's now 23), and +2 strength, which you don't. Your diet becomes restricted to the blood of sentient creatures, your alignment becomes evil if it wasn't already, and you become vulnerable to direct sunlight.

Your other vampire weaknesses want to be things that won't get in your way. Inability to enter consecrated or hallowed ground is good, since you can Desecrate twice per day at that level (3/day at level 8). Needing an invitation to go into a private home might work, if most of the dungeon isn't a private home. So would being nauseated by holy water if most enemies don't use it. At 8th level, you can also become vulnerable to silver so that it, too, bypasses your regeneration.

Other Spheres
Heresy is a nifty sphere since it makes you immune to things like Greater Turning, but you really only need Desecrate from it, which you can also get from Bone (3.5e Sphere) (which gives you unlimited zombies for free, but also makes things you finish with your spell-like abilities useless for better undead) and Venom (3.5e Sphere), which lets you poison people. So you have choices there.

You can change your damage sphere away from Frostbite. There are three other real choices for your damage sphere in this build, more if things like the Book of Elements are open. These are Cold, Fire, and Pyre. If you take Fire, and possibly if you take Pyre, you want to be Carcerian for immunity to cold when you pick your Petitioner Immunity. That way, the sphere gives you a weakness to something that you're immune to. Pyre and Fire have really nice synergy, as do Frostbite and Cold; if you pick one now it's recommended to pick up the other later if nothing else screams awesome at you.

Frostbite works best, since it gives you more targeted spells than the others do, and the battlefield is full of your minions. So it's the default choice. If you want to mix it up in melee, you probably want Pyre for Flame Blade, which lets you make touch attacks.

Seduction gives you help with mind controlling things, which is always good, but you don't really need it. You can take another damaging sphere (Cold (3.5e Sphere) goes well with Frostbite and immunity to fire, for instance, both of which you have), or advanced access to the one you already have, or another sphere full of spells that fvcking kill people instead, and you wouldn't miss much.

Other Components
You don't really need any specific skills other than a few ranks in Heal (required to make Ghasts with A Feast Unknown), but you can pick up a few things. Concentration is mandatory for casters, and Knowledge (Religion), Diplomacy, Bluff, and Disguise are all useful, if you have the intelligence to pull it off on your Conduit levels.

Highlights
This build gives you, at level 8:
 * Seven, count 'em, seven Ghasts
 * Seven Wraiths, which auto-win against most of the monster manual
 * As many Vampire Spawn as you can make.
 * A bunch of spell-like abilities at save DC 21 (22 with the cloak) and caster level 8. Highlights of this include Desecrate and Unholy Sword from Heresy, Suggestion and Charm Monster from Seduction, Cone of Cold and Shivering Touch! from Frostbite
 * Spellcasting as a 3rd level sorcerer. You don't care much, but you can take spells that aren't available in Spheres with this.
 * All your undead are at +2 hit points per hit die since they were made on Desecrated ground in the presence of an evil altar. Ideally, you would arrange for those circumstances when you get vampirized so that you can benefit from it too.
 * Regeneration 8, bypassed by critical hits, fire (immune), positive energy, aligned weapons, and wood.

Tactics
Mostly, you flood the battlefield with your minions. You have at least 14 of them, and can replace them given a supply of corpses (for the Wraiths), dying people (for the Ghasts) and living people (for the Vampire Spawn). Against single big things, you surround them and drag them down, and maybe run in with a Shivering Touch, or crowd them out with cheap undead and wear them down that way.

Further Optimization
There are a few alternate progressions for this build, and Whispers of the Otherworld is liable to get banned. You can replace it with Body Assemblage or even Path of Blood (which gives you vampire cohorts).

Also, if you can squeeze in Quicken Spell somewhere (maybe take off Heighten Spell-like Ability), you have a Blood Pool of up to 11 that you fill off of your enemies' constitution scores, and for four points of that you can quicken a spell. Whether this works on your sphere abilities is up in the air, though. If it does, you want this.

Being able to re-assign things (attack rolls, AC, and hit points) to Charisma really helps with this build. Being a Mummy instead of a Vampire costs you the Vampire Spawn and two points of Charisma (bringing you from having somewhere between fourteen and infinity minions down to twelve), but it does get you Charisma to HP. Also, you must be immune to fire. This can come from Petitioner immunities (Baator) or from the Fire sphere.

Fortification armor protects you from critical hits, which bypass your regeneration, so you might want to get that.

This build by no means stops being effective past level 8. Your vampire spawn do eventually expire, though, since they stay CR 5, but the undead from your feats keep up with you. As you level, you probably want to finish Conduit to get more spheres, and take more Necromantic Creation Feats, like Wrappings of the Ages. Some highlights: at level 13, you finish Conduit and get six levels of Sorcerer casting, stacking with the Vampire Paragon. You cast as a 9th level Sorcerer, which means that you can get some really nice backup spells like Curse of Crumbling Conviction. Quicken Spell, if you don't already have it, would also be really nice too; even if it doesn't work on your spheres; you will be able to cast four quickened spells per combat. Now you want to progress in something else.

Progression B
You start off the same as in Progression A, but take different classes.

Fighting Style
Here you have to customize and name a fighting style. There's a lot of awesome here, but you want a defensive style. Abilities like Concealment, +4 AC, and +4 saves are great. Abilities like +30' movement, move through people, and make against people who attack you are less great. Abilities like Fighting Style with a weapon and Fighting Style for con damage suck for this build. So you want styles like
 * Spectral Tiger's Dance: Concealment, +4 Dodge bonus to saving throws.
 * Playful Ghost's Dodge: +30' movement, move through people

Difference
One of the Monk's authors has specifically said that they meant Rain of Flowers to make your spells do nonlethal damage. So you do that. This makes it possible for you to drop nonlethal fireballs on people, which some of your undead minions will be outright immune to. Unfortunately, your Spawn won't be. This is why you took the Bone sphere and swapped A Feast Unknown for Body Assemblage.

If you want to make extra no-limit Zombies, you can just turn off Rain of Flowers when you incinerate your prisoners or enemies in a Wall of Fire. If you want to make vampires, just take prisoners. If you want wraiths or skeletons or something, kill them some other way. Remember that you can add undead you run into to your army with Command Undead. Simple enough. Remember that a little bit of nonlethal damage is often enough to save your enemies' life, at least long enough to provide fresh blood.

If you feel the Bone Sphere sucks, you can take Death (3.5e Sphere) instead. Your first sphere must have a Necromancy spell for its first ability to qualify for Body Assemblage, though.

Further Progression
Once again, you want to progress further as a Conduit. Also, another level of Monk gives you your second choice fighting style, if you care about such things.

Side Notes
This is a very easily-modified undead army build to suit whatever kind of undead army you think you need.

Limitations
Any build that relies on a horde of undead is vulnerable when they can't use their horde of undead. So tight passages that they have to go through single file, small rooms, and so on mess with this build a lot. So do things like armies of good clerics that can turn their undead.

Variants
As mentioned above, there are a lot of possible variations in this build; swapping one necromantic feat for another, or one sphere for another works; mummies work almost as well as vampires, too, especially in the second variant (being able to drop a nonlethal fireball on yourself is always useful).