What are some of the most horrific spells to give an evil cleric BBEG as a raid boss?

[NarcoticSqurl]

I'm putting together a "raid-boss" style villain for a one shot, and am curious what some of the more...aggressive spells would be to outfit this character with? He's a- *deep breath*

Human half-dragon vampire 20th level Cleric, with the Death domain, and a custom fear domain I found on the 3.5 wiki: https://www.dandwiki.com/wiki/Fear_(3.5e_Cleric_Domain)

Currently, I have his lair set up with a permanent desecration effect, and a zone of dispelling magic that specifically is designed to dispel any attempt at casting time based spells such as haste, time stop, temporal stasis, safety spells such as sanctuary, contingency, shield of faith, any sort of warp spells such as blink, teleport, dimensional door, etc., and either wish or miracle spells. He also has pre-summoned creatures from summon monster 6, 7, and 8 (1 per spell).

He has max gear for his mental stats (+6 to all 3), and a belt of same properties for his physical stats, as well as a cloak of resistance +5.

Right now I'm looking for spells to make him a nightmare. His title is "Lord of Fear", so I feel like the harder this encounter gets, the better. Anything PF official is acceptable, and since I'm also working with a homebrew 3.5 domain, if there are any 3.5 spells that PF doesnt have from official sources, those will work too.

[LordKailas]

Well, the following spells might work

Agonizing Rebuke
Aura of Doom
Debilitating Portent
Hydrophobia
Overwhelming Presence
Symbol of Fear

For the spells that normally only target a single creature you could slap something like contagious spell on it or since you're already borrowing from 3.5 you could just give him the feat chain spell

[Firebug]

Depends on the party composition, but Authoritative Burning Disarm? Forbid melee attack for a +2 to level and if they make their save they drop their weapon, if they fail the save they take damage and can't make melee attacks for a round. Or Dazing Spell at +3 spell level.
Or yeah, Chain if you allow it.

Quickened, Chain Burning Disarm would be a 8th level slot, with a fairly low DC... luckily it Disarms them if they save! Unless they have quickdraw and backup weapons (or they choose to automatically fail), it will shutdown full attacks.
Once they decide to start auto-failing, draw that (arguably lesser)Rod of Dazing Spell.

[LordKailas]

Another thought occurred to me. Since you're looking at 3.5 content and the BBEG is a cleric you could grab the feat Divine Metamagic. It lets you pay for metamagic level increases by burning channel energy uses. This is such an easily abused feat that our table finally had to ban it's use.

For example, my first level cleric combined it with the feat Fell Animate. Fell Animate tacks an animate dead spell to anything you kill with the spell at a cost of +3 spell levels. This combination let me grab a 2 HD zombie at 1st level. One of the tamer combinations we discovered.

[Ryze Kuja]

Firstly, I'd recommend having this spell up before combat begins (as it will work very nicely with Overwhelming Presence):

Frightful Aspect wrote:

Frightful Aspect

School transmutation (polymorph); Level cleric 8, druid 8, sorcerer/wizard 8, witch 8

CASTING

Casting Time 1 standard action
Components V, S, M (the skin of a toad)

EFFECT

Range personal
Target you
Duration 1 minute/level

DESCRIPTION

You become a larger, awful version of yourself. You grow to size Large, and take on features that horrify your enemies. You gain the following abilities: a +6 size bonus to Strength, a +4 size bonus to Constitution, a +6 natural armor bonus, DR 10/magic, and spell resistance equal to 10 + half your caster level. You also emit an aura that emanates 30 feet from you. Enemy creatures within the aura are shaken. Each time a creature shaken by this aura hits you with a melee attack, that creature becomes frightened for 1d4 rounds, though at the end of that duration it is no longer affected by this aura. The aura’s effect is a fear and mind-affecting effect.

Also,

Curse Terrain, Supreme wrote:

Curse Terrain, Supreme

School necromancy [curse, evil]; Level cleric 8, druid 8, shaman 8, sorcerer/wizard 8, witch 8
Components V, S, M (the heart of a creature that dwelled in the area and powdered onyx worth 4,000 gp)

EFFECT

Range touch
Area 5-mile radius emanating from the touched point

DESCRIPTION

By touching the ground, you curse the land with seven unnatural hazards. This functions as lesser curse terrain, but with the effects of the grand perilous demesne curse.

With 7 hazards at your disposal, you can have Inverted Gravity, No Gravity, High Gravity, Dense Smoke, Lava, Acid, Catching on Fire, etc.

Pick anything you deem appropriate: Environmental Hazards or Cursed Land

At level 13, you can take the feat Dreamed Secrets, which gives you access to 2 wizard spells per day but they can only be spells 1 level lower than the Divine spells you can cast. So you can pick two 8th lvl or lower Wizard spells to shore up your Cleric spells. I'd recommend any combo of the following (remember that you can choose any of these Wizard spells you want every day when you prepare your spells, so if you want to do Clones and Contingencies days/weeks/months beforehand, you can):

Moment of Prescience (+25 to any d20 roll)
Polymorph Any Object
Form of the Dragon III
Clone (so your BBEG can still live to fight another one-shot campaign ;) )
Greater Shadow Evocation (so you can mirror any Evocation spell you might want)
Power Word Stun (as soon as you think they're 150HP or less, let 'em have it)
Prediction of Failure (can be fun, keeps in touch with being the Lord of Fear)
Spell Turning
Limited Wish (for -7 debuff to one of their Saves)
Waves of Exhaustion (No Save)
Mass Fly/Invis (for your Summons/Minions)
OR...
If you really want to get froggy with some True Strike/Disintegrate shenanigans, get Spell Perfection at lvl 15 and prepare a Persistent Disintegrate as a lvl 6 spell slot (or Empowered Persistent Disintegrate as lvl 8 slot).

Quickened True Strike + Persistent Spell Perfected Disintegrate = ~95% accuracy 40d6 nuke and save Twice.

Quickened True Strike + Empowered Persistent Spell Perfected Disintegrate = ~95% accuracy 40d6 (+50%) nuke and save Twice.

OR...

Quickened True Strike + Maximized Empowered Touch of Idiocy = 5% miss chance No Save -9 Int/Wis/Cha

Quickened True Strike + Maximized Empowered Spell Perfected Enervation = 5% miss chance No Save -6 Negative Levels

..

Also, since you are homebrewing, why not create your own Power Word: Fear spell. Anything with 200hp or less gets feared for 1d4 rounds (or whatever you think is balanced)

[NarcoticSqurl]

Wow, thank you guys/gals for all the brilliant suggestions. This all helps flesh out the villain concept some more as well. Seems like some of the suggestions were things that I missed while going through my books, so thanks for bringing those to my attention. It can be hard to keep a hard focus on a theme when theres so many books to poor over.