Trainz
Explorer
I used the hit-dice advancment rules to boost a Balor. It took me so long, that I decided to post it here. Note that at CR 35, it is quite an epic critter.
So here he is, the Greater Balor:
Balor, Greater Huge Outsider (Chaotic, Extraplanar, Evil)
HD 50d8+600; hp 825;
Init +10;
Spd 40 ft., fly 90 ft. (good);
Space/Reach 15 ft./15 ft. (30 ft. with +1 flaming whip);
AC 56 (-2 size, +6 Dex, +42 natural), touch 14, flat-footed 50;
Base Atk +50; Grp +76;
Atk +3 unholy vorpal longsword +70 melee (2d6(unholy)+3d6+23/19-20);
Full Atk +3 unholy vorpal longsword +70/+65/+60/+55 melee (2d6(unholy)+3d6+23/19-20) and +5 flaming unholy whip +71/+66 melee (2d6(unholy)+1d6+16 plus 1d6 fire plus entangle); or 2 slams +68 melee (2d8+15);
SA Death throes, entangle, spell-like abilities, summon demon, vorpal sword;
SQ Damage reduction 15/cold iron and good, darkvision 60 ft., flaming body, immunity to electricity, fire, and poison, resistance to acid 10 and cold 10, spell resistance 28, telepathy 100 ft., true seeing;
AL Always chaotic evil;
SV: Fort +39, Ref +34, Will +34;
Abilities: Str 50, Dex 23, Con 35, Int 24, Wis 24, Cha 26
Skills: Bluff +61, Concentration +63, Diplomacy +65, Disguise +38 (+40 acting), Hide +56, Intimidate +63, Knowledge (any two) +60, Listen +68, Move Silently +60, Search +60, Sense Motive +60, Spellcraft +60 (+62 scrolls), Spot +68, Survival +37 (+39 following tracks), Use Magic Device +61 (+63 scrolls)
Feats: Cleave, Improved Initiative, Improved Two-Weapon Fighting, Power Attack, Quicken Spell-Like Ability (telekinesis), Two-Weapon Fighting, Weapon Focus (longsword), natural armor +20
CR: 35
Skills: Balors have a +8 racial bonus on Listen and Spot checks.
Spell-Like Abilities: At will- blasphemy (DC 25), dominate monster (DC 27), greater dispel magic, greater teleport (self plus 50 pounds of objects only), insanity (DC 25), power word stun, telekinesis (DC 23), unholy aura (DC 26); 1/day-fire storm (DC 26), implosion (DC 27). Caster level 50th. The save DCs are Charisma-based.
Entangle(Ex): A balor's +5 flaming whip entangles foes much like an attack with a net. The whip needs no folding. If it hits, the target and the balor immediately make opposed Strength checks; if the balor wins, it drags the target against its flaming body (see below). The target remains anchored against the balor's body until it escapes the whip.
Flaming Body(Su): The body of a balor is wreathed in flame. Anyone grappling a balor takes 6d6 points of fire damage each round.
Summon(Sp): Once per day a balor can automatically summon 4d10 dretches, 1d4 hezrous, or one nalfeshnee, glabrezu, marilith, or balor. This ability is the equivalent of a 9th-level spell.
Tactics Round-by-Round: Unholy aura. Round 1: Fire storm or implosion and quickened telekinesis, or summon additional demons. If the balor does not deem itself seriously threatened, it conserves abilities usable only once per day and uses blasphemy instead. Round 2: Insanity or power word stun. Round 3: Full melee attack with weapons, including entangle with whip. Round 4: Teleport or fly away with entangled foe to reestablish range; repeat round 1 and continue. A balor who wants to drive off or neutralize a party without slaying its foes avoids lethal attacks. Prior to combat: Unholy aura. Round 1: Dominate monster. Round 2: Power word stun. Round 3: Insanity or telekinesis to incapacitate or repel a dangerous opponent. Round 4: Teleport or fly away to reestablish range; repeat round 1 and continue.
True Seeing(Su): Balors have a continuous true seeing ability, as the spell (caster level 50th).
Death Throes(Su): Same as regular Balors.
So here he is, the Greater Balor:
Balor, Greater Huge Outsider (Chaotic, Extraplanar, Evil)
HD 50d8+600; hp 825;
Init +10;
Spd 40 ft., fly 90 ft. (good);
Space/Reach 15 ft./15 ft. (30 ft. with +1 flaming whip);
AC 56 (-2 size, +6 Dex, +42 natural), touch 14, flat-footed 50;
Base Atk +50; Grp +76;
Atk +3 unholy vorpal longsword +70 melee (2d6(unholy)+3d6+23/19-20);
Full Atk +3 unholy vorpal longsword +70/+65/+60/+55 melee (2d6(unholy)+3d6+23/19-20) and +5 flaming unholy whip +71/+66 melee (2d6(unholy)+1d6+16 plus 1d6 fire plus entangle); or 2 slams +68 melee (2d8+15);
SA Death throes, entangle, spell-like abilities, summon demon, vorpal sword;
SQ Damage reduction 15/cold iron and good, darkvision 60 ft., flaming body, immunity to electricity, fire, and poison, resistance to acid 10 and cold 10, spell resistance 28, telepathy 100 ft., true seeing;
AL Always chaotic evil;
SV: Fort +39, Ref +34, Will +34;
Abilities: Str 50, Dex 23, Con 35, Int 24, Wis 24, Cha 26
Skills: Bluff +61, Concentration +63, Diplomacy +65, Disguise +38 (+40 acting), Hide +56, Intimidate +63, Knowledge (any two) +60, Listen +68, Move Silently +60, Search +60, Sense Motive +60, Spellcraft +60 (+62 scrolls), Spot +68, Survival +37 (+39 following tracks), Use Magic Device +61 (+63 scrolls)
Feats: Cleave, Improved Initiative, Improved Two-Weapon Fighting, Power Attack, Quicken Spell-Like Ability (telekinesis), Two-Weapon Fighting, Weapon Focus (longsword), natural armor +20
CR: 35
Skills: Balors have a +8 racial bonus on Listen and Spot checks.
Spell-Like Abilities: At will- blasphemy (DC 25), dominate monster (DC 27), greater dispel magic, greater teleport (self plus 50 pounds of objects only), insanity (DC 25), power word stun, telekinesis (DC 23), unholy aura (DC 26); 1/day-fire storm (DC 26), implosion (DC 27). Caster level 50th. The save DCs are Charisma-based.
Entangle(Ex): A balor's +5 flaming whip entangles foes much like an attack with a net. The whip needs no folding. If it hits, the target and the balor immediately make opposed Strength checks; if the balor wins, it drags the target against its flaming body (see below). The target remains anchored against the balor's body until it escapes the whip.
Flaming Body(Su): The body of a balor is wreathed in flame. Anyone grappling a balor takes 6d6 points of fire damage each round.
Summon(Sp): Once per day a balor can automatically summon 4d10 dretches, 1d4 hezrous, or one nalfeshnee, glabrezu, marilith, or balor. This ability is the equivalent of a 9th-level spell.
Tactics Round-by-Round: Unholy aura. Round 1: Fire storm or implosion and quickened telekinesis, or summon additional demons. If the balor does not deem itself seriously threatened, it conserves abilities usable only once per day and uses blasphemy instead. Round 2: Insanity or power word stun. Round 3: Full melee attack with weapons, including entangle with whip. Round 4: Teleport or fly away with entangled foe to reestablish range; repeat round 1 and continue. A balor who wants to drive off or neutralize a party without slaying its foes avoids lethal attacks. Prior to combat: Unholy aura. Round 1: Dominate monster. Round 2: Power word stun. Round 3: Insanity or telekinesis to incapacitate or repel a dangerous opponent. Round 4: Teleport or fly away to reestablish range; repeat round 1 and continue.
True Seeing(Su): Balors have a continuous true seeing ability, as the spell (caster level 50th).
Death Throes(Su): Same as regular Balors.
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. Good work man.
Anger Demon folks! They mean ANGRY! 
