Weapon and Armor Proficiency: A disciple of Ashardalon gains no proficiency with any weapons, armor, or shields.

Fiendbond (Su): As part of its initiation, a disciple of Ashardalon binds a demonic spirit to its own heart, emulating the manner in which Ashardalon himself took a balor as his heart. The dragon's alignment changes to chaotic evil if it was not already of that alignment. The dragon gains bonus sorcerer spells as if its Charisma score were 2 points higher than actual.

Resistance (Ex): A disciple of Ashardalon gains resistance to acid, cold, electricity, and fire. This resistance is 5 at 1st level, and increases by 5 at 4th level and every four levels thereafter (10 at 4th level, 15 at 8th level, and 20 at 12th level).

Spell-Like Abilities: A disciple of Ashardalon gains spell-like abilities as it increases in level. Its caster level is equal to its class level, and its saving throw DCs are 10 + its Cha modifier + spell level. Once an ability is gained, the disciple can use it a certain number of times per day, as follows: 3/day— darkness, poison, unholy aura; 1/day— blasphemy, contagion, desecrate, destruction, horrid wilting, unhallow, unholy aura, unholy blight.

Skill Point Increase: At 2nd level, and again at 10th level, a disciple of Ashardalon gains a pool of bonus skill points equal to the number of dragon Hit Dice it possesses. This pool represents a gradual transition from being a creature of the dragon type (with 6 skill points per HD) to being an outsider (with 8 skill points per HD). These bonus skill points are in addition to the skill points gained at every level, and are not modified by the dragon's Intelligence score.

Ability Increase: Every three levels, a disciple of Ashardalon's ability scores increase automatically. At 3rd, 6th, 9th, and 12th level, its Strength, Dexterity, and Intelligence all increase by 1 point. At 6th and 12th level, its Constitution and Charisma also increase by 1 point. By 12th level, a disciple of Ashardalon has the ability score adjustments of the half-fiend template.

Poison Immunity (Ex): A disciple of Ashardalon of 6th level or higher is immune to all forms of poison.

Natural Armor Increase (Ex): At 7th level, a disciple of Ashardalon's natural armor bonus improves by 1.

Fiendish Perfection (Ex): At 12th level, a disciple of Ashardalon's bond with its demonic spirit is complete and perfect. The dragon now has the half-fiend template and becomes an outsider rather than a dragon.