Updating the stat block to speed things along...
Rilmani, Argenach
Medium Outsider (Extraplanar, Rilmani)
Hit Dice: 14d8+84 (147 hp)
Initiative: +3
Speed: 40 ft (8 squares)
Armor Class: 21 (+3 Dex, +8 natural), touch 13, flat-footed 18
Base Attack/Grapple: +14/+21
Attack:
+3 greatsword +21 melee (2d6+10/19-20)
Full Attack: Silvery rays +17/+12 ranged touch (1d20 energy) or
+3 greatsword +21/+16/+11 melee (2d6+10/19-20)
Space/Reach: 5 ft/5 ft
Special Attacks: Spell-like abilities, summon rilmani, silvery rays
Special Qualities: Damage reduction 15/good or evil or lawful or chaotic, darkvision 60 ft, immunity to electricity and poison, lay on hands (?), resistance to acid 10 and sonic 10, spell resistance 22
Saves: Fort +15 Ref +12 Will +12
Abilities: Str 24, Dex 17, Con 22, Int 16, Wis 16, Cha 19
Skills: 187 (Ranks--Bluff 17, Concentration 14, Diplomacy 16, Disguise 14, Gather Information 14, Intimidate 14, Knowledge (any two) 14, Knowledge (the planes) 14, Listen 14, Search 14, Spot 14, Sense Motive 14?)
Feats: 5 (Negotiator, Persuasive, Point Blank Shot, Precise Shot, Weapon Focus ([energy ray])?
Environment: Concordant Domain of the Outlands
Organization: Solitary or band (1-4)
Challenge Rating: X
Treasure: No coins, double goods, standard items
Alignment: Always neutral
Advancement: 15-28 HD (Medium); 29-42 (Large)
Level Adjustment: +X
This tall, slender humanoid has a silvery sheen to its skin. It is smooth-skinned and hairless, and wears white, flowing robes and wields a greatsword.
An argenach is 7 feet tall and weighs 225 pounds.
An argenach can speak Rilmani, Common, Undercommon.
COMBAT
Energy Rays (Su): Twice per round, an argenach may fire a ray of silvery light projected from its hands. These rays inflict 1d20 points of damage, and always strike as an energy form that exploits an enemy's vulnerabilities: acid, cold, electricity, fire, sonic, positive energy or negative energy. For example, baatezu are immune to fire and resistant to acid and cold, so the argenach's rays might strike as electricity or sonic energy. If a creature has vulnerability to a certain energy type, such as vulnerability to cold for creatures with the fire subtype, the argenach's rays will exploit this vulnerability over other energy types. These rays have a range of 180 feet.
Summon Rilmani (Sp): Once per day, an argenach can summon 1d4 ferrumachs with a 60% chance of success or another argenach with a 40% chance of success. This ability is the equivalent of an Xth-level spell. (A ferrumach can be summoned using summon monster VII, so 1d4 would seem to be summon monster VIII. However, a cuprilach is on the summon monster IX list, and the argenach should be of at least a comparable level to a cuprilach, so I think it should be the equivalent of a 9th-level spell.)