Well, a Minotaur Sorcerer 13 is a CR 14 creature. With only the standard array, he'll have only started with a 13 Charisma, though; using all his stat bumps, he'll just have gotten to Charisma 16, and thus able to use all his spell levels.
If you go with point buy (especially higher point buy) or some other method, he can have better stats and DC's.
Anyway, I found the challenge intriguing, so here is a quick build, using only the elite array. He's missing a few spells yet, and some feats, but you can fill those in to fit your adventure. You could easily swap out Improved Bull Rush and Shock Trooper for Combat Reflexes and Large and in Charge (Draconomicon), especially if you go to a point buy method that grants a higher Dexterity.
He also needs equipment. Lots of Wands and Scrolls to cover his missed areas would be good.
Minotaur Sorcerer 13
Large Monstrous Humanoid
Hit Dice: 6d8 +13d4 +76 (135 hp)
Initiative: +1
Speed: 30 ft. (6 squares)
Armor Class: 15 (–1 size, +1 Dex, +5 natural), touch 10, flat-footed — (see text)
Base Attack/Grapple: +12/+19
Attack: Greataxe +14 melee (3d6+4/x3) or gore +14 melee (1d8+3) or melee touch +14 or ranged touch +12
Full Attack: Greataxe +14/+9/+4 melee (3d6+4/x3) and gore +9 melee (1d8+1)
Space/Reach: 10 ft./10 ft.
Special Attacks: Powerful charge 4d6+4
Special Qualities: Darkvision 60 ft., natural cunning, scent
Saves: Fort +10, Ref +10, Will +14
Abilities: Str 16, Dex 13, Con 18, Int 6, Wis 12, Cha 16
Skills: Concentration +17 [13 ranks], Intimidate +4 [1 ranks], Listen +9 [4 ranks], Search +2 [0 ranks], Spot +9 [4 ranks]
Feats: Power Attack, Improved Bull Rush, Shock Trooper, Practiced Spellcaster, 12
Environment: Underground
Organization: Solitary, pair, or gang (3–4)
Challenge Rating: 14
Treasure: Standard
Alignment: Usually chaotic Evil
Advancement: By character class
Level Adjustment: +2
A minotaur stands more than 7 feet tall and weighs about 700 pounds.
Minotaurs speak Giant.
COMBAT
Minotaurs prefer melee combat, where their great strength serves them well.
Powerful Charge (Ex): A minotaur typically begins a battle by charging at an opponent, lowering its head to bring its mighty horns into play. In addition to the normal benefits and hazards of a charge, this allows the beast to make a single gore attack with a +9 attack bonus that deals 4d6+4 points of damage.
Natural Cunning (Ex): Although minotaurs are not especially intelligent, they possess innate cunning and logical ability. This gives them immunity to maze spells, prevents them from ever becoming lost, and enables them to track enemies. Further, they are never caught flat-footed.
Skills: Minotaurs have a +4 racial bonus on Search, Spot, and Listen checks.
Spells: Caster Level 17th (Save DC 13 +spell level)
Level (Per Day) - Spells Known
0 (6) - 9 Detect Magic, Detect Poison, Read Magic, Dancing Lights, Mage Hand, Prestidigitation, Caltrops SpC, X, X
1 (7) - 5 Mage Armor, Magic Missile, True Strike, Expeditious Retreat, Ray of Exhaustion
2 (7) - 5 Resist Energy, Touch of Idiocy, Mirror Image, Scorching Ray, Glitterdust or Web (Heroics SpC, would be another good option, As would Wraithstrike)
3 (7) - 4 Displacement, Vampiric Touch, Greater Magic Weapon, Ray of Dizziness SpC
4 (6) - 4 Evard's Black Tentacles, Heart of Earth CM, Dimension Door, Orb of Acid
5 (6) - 3 Cloudkill, Acid Sheath SpC, X (Prying Eyes might be good for finding intruders in your lair/maze)
6 (4) - 2 Greater Dispel Magic, Disintegrate
