I'm working on one, I'll post it when done.
EDIT - Here it is, I only used the SRD, no splatbook or other non-SRD WotC books.
“The Harvester” – Male ½ Fiend/Centaur Blk10/Ftr5/Rog10: CR 30; Size Large Outsider; Face/Reach 5x10/5; HD 4d8+28+5d10+35+10d6+70+10d10+70; hp 232(min) 349(avg) 445(max); Init +3 (+3 Dex); Spd 50 ft., Fly 50’ (avg); AC 15 (-1 size, +3 Dex, +3 Natural); Attack +35/+30/+25/+20 melee, 2 hooves +30 melee (hoof damage 1d6+5), Bite +30 melee (1d8+5), 2 Claws +30 melee (1d6+5) or +28/+23/+18/+13 ranged; SV Fort +29, Ref +19, Will +19; AL CE; Str 30, Dex 17, Con 25, Int 18, Wis 18, Cha 18. [Note- the above are base stats from creature, template, class, racial modifiers before any equipment/magic adjustment][Manuals & Tomes add +5 inherit bonus to Str, Dex, Con, Int, Wis and Cha are not reflected in the above]
Adjusted Base Stats: Size Large Outsider; Face/Reach 5x10/5; HD 4d8+40+5d10+50+10d6+100+10d10+100; hp 319(min) 391(avg) 532(max); Init +6 (+6 Dex); Spd 70 ft., Fly 35’ (avg); AC 38 (-1 size, +13 Armor, +7 Shield, +5 Deflection, +1 Dex, +3 Natural); Attack +40/+35/+30/+25 melee, 2 hooves +35 melee (hoof damage 1d6+7), Bite +35 melee (1d8+7), 2 Claws +35 melee (1d6+7) or +31/+28/+21/+16 ranged; SV Fort +36, Ref +26, Will +28; AL CE; Str 35(41 w/ Belt of Giant Strength)[+12/+15 mod], Dex 22[+6 mod], Con 30[+10 mod], Int 23[+7 mod], Wis 23(29 w/ Periapt of Wisdom)[+7/+9 mod], Cha 23(27 w/Rod of Splendor)[+6/+8 mod]
Attacks:
+41/+36/+31/+26 melee:
+5 Huge Adamantine Keen, Chaotic, Unholy Bastard Sword –
Dmg 2d6+22+2d6(vs. Good)+2d6(vs. Law), 15-20/x2
+35 melee: 2 Hooves– Dmg 1d6+7
+35 melee: Bite– Dmg 1d8+7
-or-
+41/+38/+31/+26 ranged:
+5 Unholy, Chaotic, Huge Mighty Composite Longbow(+4 STR) w/ +5 Bane Arrows –
Dmg 2d6+9+2d6(vs. Law)+2d6(vs. Good)+2d6(Bane vs. selected race)
Special Attacks: Sneak Attack +8d6, Spells (Blackguard: Base DC 19+Sp Lvl, 10th lvl caster), Smite Good +10 (1/day)
Special Qualities: Uncanny Dodge (Dex to AC, can’t be flanked), Improved Evasion (1/2 dmg on failed save), Poison Use (cannot poison himself), Detect Good at will, Dark Blessing (add Cha mod to saves), Aura of Despair, Command Undead (as 8th lvl Clr, 10/day), Spells, Darkvision 60’, Immune to poison, and Acid, Cold, Electricity, and Fire Resistance 20. Spell-like abilities (caster level equals character level): Darkness (3/day), Desecrate (1/day), Unholy blight (1/day), Poison (3/day), Contagion (1/day), Blasphemy (1/day), Unholy aura (3/day), Unhallow (1/day), Horrid Wilting (1/day), Summon monster IX (fiends only) (1/day),Destruction (1/day), Fiendish Servant
Languages Spoken: Elven, Sylvan, Common, Abyssal, Draconic, Ignan.
Skill points: ½ Fiend Centaur 48, Ftr 30, Rog 120, Blk 60 [assume Int gained last level, default Int 18 through career], total 258
Skills: Centaur Class Skills: Hide (Dex), Listen (Wis), Move Silently (Dex), Spot (Wis), Wilderness Lore (Wis).
Fighter Class Skills: Climb (Str), Craft (Int), Handle Animal (Cha), Jump (Str), Ride (Dex), and Swim (Str).
Rogue Class Skills: Appraise (Int), Balance (Dex), Bluff (Cha), Climb (Str), Craft (Int), Decipher Script (Int, exclusive skill), Diplomacy (Cha), Disable Device (Int), Disguise (Cha), Escape Artist (Dex), Forgery (Int), Gather Information (Cha), Hide (Dex), Innuendo (Wis), Intimidate (Cha), Intuit Direction (Wis), Jump (Str), Listen (Wis), Move Silently (Dex), Open Lock (Dex), Perform (Cha), Pick Pocket (Dex), Profession (Wis), Read Lips (Int, exclusive skill), Search (Int), Sense Motive (Wis), Spot (Wis), Swim (Str), Tumble (Dex), Use Magic Device (Cha, exclusive skill), and Use Rope (Dex).
Blackguard Class Skills: Concentration (Con), Craft (Int), Diplomacy (Cha), Handle Animal (Cha), Heal (Wis), Intimidate (Cha), Knowledge (religion) (Int), Profession (Wis), and Ride (Dex).
Skill Ranks Purchased:
½ Fiend/Centaur (max 7): Hide 7, Listen 7, Move Silently 7, Spot 7, Wilderness Lore 6, Know(religion) 3, Know(Arcana) 3, Know(the planes) 1.
Fighter (max 13): Climb 10, Jump 10, Swim 10.
Rogue (max 23): Bluff 23, Hide 16, Intimidate 8, Listen 16, Move Silently 16, Search 10, Sense Motive 15, Spot 16.
Blackguard (max 33): Concentration 15, Diplomacy 15, Intimidate 15, Know(religion) 15.
Skill Totals with Stat modifiers and Armor Check Penalties: Bluff +31, Concentration +25, Climb +19, Diplomacy +23, Hide +23, Intimidate +31, Jump +19, Know(religion) +25, Know(arcane) +10, Know(the planes) +8, Listen +32, Move Silently +23, Search +17, Sense Motive +24, Spot +32, Swim +19, Wilderness Lore +15.
Feats: Power Attack, Cleave, Sunder, Exotic Weapon Proficency (Huge Bastard Sword), Weapon Focus (Huge Bastard Sword), Weapon Specialization (Huge Bastard Sword), Improved Critical (Huge Bastard Sword), Leadership [taken at 28th level, leadership modifiers for Failure(-1)(imprisioned once), Aloofness(-1), Cruelty(-2) and Special Power(+1), Cha modifier (+4) for results 25+ on the Leadership Table. This should help raise an army or attract a cohort within 1d4 months when he is released.
Leadership Cohort -- Number of Followers by Level --
Score Level 1st 2nd 3rd 4th 5th 6th
---------- --- --- --- --- --- --- --- ---
25+ 17th 135 13 7 4 2 2
Spell List:
1st level—cause fear, cure light wounds, doom, inflict light wounds, magic weapon, summon monster I*.
2nd level—bull’s strength, cure moderate wounds, darkness, death knell, inflict moderate wounds, shatter, summon monster II*.
3rd level—contagion, cure serious wounds, deeper darkness, inflict serious wounds, protection from elements, summon monster III*.
4th level—cure critical wounds, freedom of movement, inflict critical wounds, poison, summon monster IV*.
*Evil creatures only.
Class ———— Spells per Day ————
Level 1st 2nd 3rd 4th
----- --- --- --- ---
10th 2 2 2 1
Bonus 3 2 2 2
----- --- --- --- ---
Total 5 4 4 3
Memorized:
1st level – cause fear, cure light wounds(x2), inflict light wounds, doom
2nd level – cure moderate wounds(x2), darkness, death knell, inflict moderate wounds
3rd level – cure serious wounds (x2), deeper darkness, inflict serious wounds
4th level – freedom of movement, cure critical wounds, inflict critical wounds
“Gloombringer” – Fiendish Male Bat Servant: CR -; Diminutive Magical Beast (evil, chaotic); Face/Reach 1’x1’/0; HD 8 ¼ d8; hp 33; Init +2 (+2 Dex); Spd 5 ft., Fly 40’ (good); AC 23 (+2 Dex, +4 size, +7 natural armor); Attack - ; SQ Blindsight 120’, empathic bond, improved evasion, cold & fire resistance 15, share saving throws, speak with blackguard, blood bond, spell resistance 15, DR 5/+2; SV Fort +18, Ref +14 (masters base save plus bat stat mod), Will +13; AL CE; Str 5, Dex 15, Con 10, Int 9, Wis 14, Cha 4. Skills: Listen +9, Move Silently +6, Spot +9
Possessions: 1,988,310 gp in gear, 2,244,090 gp (to spend for hidden/forgotten fortress).
Huge Adamantine Bastard Sword - “Doomsong” - +5 Huge Adamantine Keen, Chaotic, Unholy Bastard Sword – 2d6 dmg. (+2d6 dmg. against Lawful, +2d6 dmg. against Good) Threat/Crit: 17-20/x2. Cost: 236,670 gp
Black Adamantine Full Plate Armor (Large x2 base cost, Non-humanoid x2 base cost, net x3 cost)- +5 Adamantine Full Plate of Heavy Fortification (100% to negate criticals, sneak attacks). AC +13, Max Dex +1, Armor Check Penalty –6. Cost: 134,500 gp
Black Adamantine Shield – (Large x2 base cost) - +5 Adamantine Huge Shield of Spell Resistance (SR19) – AC +7, -2 Check Penalty. Cost: 102,340 gp.
Huge Mighty Composite Longbow (+4 STR) - +5 Unholy, Chaotic, Huge Mighty Composite Longbow(+4 STR) – 2d6+4 dmg. (+2d6 dmg. against Lawful, +2d6 dmg. against Good). Cost: 210,600 gp.
Quiver of Elhonna – 1,800 gp.
+5 Bane Arrows (qty =50) – determine type specific to campaign. 98,000 gp.
Ring of Spell Turning – 150,000 gp.
Ring of Protection +5 – 50,000 gp.
Rod of Splendor – as long as carried or held, +4 enhancement bonus to Charisma score, plus other powers. Cost: 25,000 gp.
Belt of Giant Strength +6 – Cost: 36,000 gp.
Major Cloak of Displacement – Cost 50,000 gp.
Gauntlet of Rust (single gauntlet) – Cost: 11,500 gp.
Glove of Storing – (single glove) – Cost: 2,200 gp.
Gem of Seeing – Cost: 75,000 gp.
Helm of Teleportation – Cost: 48,600 gp.
Heward’s Handy Haversack – Cost: 2,000 gp.
Horseshoes of Speed – Base move is 50’. Wearing Heavy Armor – 35’. Doubled to 70’. Cost: 1,900 gp.
Manual of Bodily Health – Already read, blank. Cost: 137,000 gp.
Manual of Gainful Exercise – Already read, blank. Cost 137,000 gp.
Manual of Quickness of Action - Already read, blank. Cost 137,000 gp.
Peripat of Wisdom +6 – Cost 36,000 gp.
Tome of Clear Thought - Already read, blank. Cost 137,000 gp
Tome of Leadership and Influence - Already read, blank. Cost 137,000 gp.
Tome of Understanding - Already read, blank. Cost 137,000 gp.
Background: In ages past, Evil roamed the hearts of forests along with good. Such evil came upon a lone centaur maiden in the deep forest, and when it left the maiden was comatose and pregnant. A Male child was born of that unholy union, gifted (or some may say cursed) with the traits of both his parents. Driven from the centaur tribe before his name day, he wandered in the wilds, harboring his hatred of those who cast him out. Seeking out other evil inhabiting the woods, he trained, learning the way of war. On his name day, he named himself “The Harvester” and began to take his fight back to those who cast him aside. Calling upon his father, The Harvester learned the ways of the knife in the night and rose in his fathers graces, trained by the infernal legions to be a champion made flesh. Until the Day of Failure, the Day of Imprisonment. On that day, all The Harvester’s plan came to a halt, stopped by the forces of Good. Now imprisioned, he dreams of a time when he shall be free, free to continue the reaping of any who oppose him….
2ND EDIT - I tried to break down everything as far as I could so you could remove things that were taken from him, etc. Let me know if you find any errors, it's my first shot designing something this high of a level...