Hrmmm......
Sun Rider
Alignment: Any
Hit Dice: d8
Level...Attack...Fort...Ref...Will...Special
1..........+1.........+0.....+2.....+0....Fire Resistance 2, Fire Affinity I, Fiery
................................................Steed, Fighter Level Transparency
2..........+2.........+0.....+3.....+0....Burning Strike 1/day, Elemental Form I
3..........+3.........+1.....+3.....+1....Fire Resistance 4, Fire Affinity II
4..........+4.........+1.....+4.....+1....Bonus Feat
5..........+5.........+1.....+4.....+1....Fire Resistance 6, Fire Affinity III
6..........+6.........+2.....+5.....+2....Elemental Form II, Fire Shield 1/day
7..........+7.........+2.....+5.....+2....Fire Resistance 8, Fire Affinity IV
8..........+8.........+2.....+6.....+2....Bonus Feat
9..........+9.........+3.....+6.....+3....Elemental Form III, Sunburst 1/day
10........+10........+3.....+7.....+3....Fire Subtype
Prerequisites:
BAB +10 or greater
Base Fortitude save +5 or greater
Knowledge (the planes, or inner planes, or elemental plane of fire) 2+ ranks
Handle Animal 5+ ranks
Ride 5+ ranks
Feats: Power Attack, Dodge, Weapon Focus, Improved Initiative
Language: Must speak Ignan
Special: Proficiency in all simple and martial weapons
(you can change the prerequisites for whatever you have in mind, of course)
Class Skills: Craft, Handle Animal, Intimidate, Knowledge (the planes), Listen, Ride, Spot.
Skill Points Per Level: 2 + Intelligence modifier
Weapon/Armor Proficiency: Sun Riders gain no new proficiencies in any weapons, armors, or shields.
Fighter Level Transparency: A Sun Rider counts their levels in this prestige class towards their levels of Fighter, if any, for purposes of determining what feats they qualify for, such as Weapon Specialization, Greater Weapon Specialization, and Greater Weapon Focus. If the Sun Rider has no levels of Fighter, they count their Sun Rider levels as Fighter levels for purposes of gaining access to these feats.
Fire Resistance: As per its description in the Monster Manual.
Fire Affinity: Gains +1 on saves against Fire damage or anything with the Fire or Light descriptor, increases to +2 at 3rd-level, +3 at 5th, and +4 at 7th. Suffers an equivalent penalty on saves against Cold damage and anything with the Cold or Water descriptor. Suffers +1 damage from Cold damage effects, which increases to +2 damage at 3rd-level, +3 at 5th, and +4 at 7th. Extraordinary ability.
Burning Strike: Supernatural ability, useable once per day. May be activated just before a normal melee attack, and activation takes no action in and of itself. That attack roll gets a +4 bonus, and if the attack is successful, it deals bonus fire damage equal to the Sun Rider's level in this prestige class + the Sun Rider's highest modifier amongst Intelligence, Wisdom, and Charisma.
Elemental Form: Gains immunity to sleep effects and acquires darkvision out to 60 feet at 2nd-level. At 6th-level, gains immunity to all poisons and gains immunity to blindness and dazzling from exposure to light, such as staring directly at the sun. The Sun Rider's Fiery Steed also gains the immunity to blindness and dazzling from exposure to light. At 9th-level, gains immunity to stunning and paralysis, as well as the capacity to ignore the Damage Reduction of all creatures with the elemental (fire) type. Supernatural ability.
Bonus Feats: A Sun Rider gains a bonus feat at 4th-level and again at 8th-level, chosen from the same list of feats as the Fighter. As with a Fighter, they must meet the normal prerequisites for these bonus feats.
Fire Shield: Spell-like ability useable once per day, functions as per the spell cast by a sorcerer of the Sun Rider's character level. However, any save DC against it is 10 + the level of the spell + the Sun Rider's highest modifier amongst Intelligence, Wisdom, and Charisma. While the Sun Rider is mounted upon his or her Fiery Steed, the Fire Shield, if active, shifts to encompass the Fiery Steed as well.
Sunburst: Spell-like ability useable once per day, functions as per the spell cast by a druid of the Sun Rider's character level. However, any save DC against it is 10 + the level of the spell + the Sun Rider's highest modifier amongst Intelligence, Wisdom, and Charisma. Does not harm the Sun Rider's own Fiery Steed.
Fire Subtype: Sun Riders eventually gain the Fire subtype, with all the associated benefits and penalties. They lose the Fire Affinity ability.
Fiery Steed: All Sun Riders receive a special mount upon taking this class, appearing from the Elemental Plane of Fire. This special mount is typically a fire-element griffon (that is, a griffon with the fire-element template from Manual of the Planes). The Fiery Steed possesses all the standard capabilities and statistics of a fire-element griffon, including having the elemental (fire) type rather than the beast or magical beast type, and it can speak Ignan. It is not like a Paladin's special mount, however. Initially, it possesses an empathic link with the Sun Rider, as per that of a sorcerer's familiar, allowing telepathic communication between the Fiery Steed and the Sun Rider. In addition, the Fiery Steed can use its own base saving throws or those of its master, whichever is most favorable at any given time.
The Sun Rider is not harmed by the heat and flames of his or her own Fiery Steed, and the Sun Rider may equip their Fiery Steed with whatever riding accoutrements he or she has, such as saddlebags, a bit and bridle, an exotic war saddle, a cart, or whatever. Such accoutrements, as long as they are placed on the Fiery Steed by the Sun Rider, will not be affected by the Steed's heat and flames, nor those of the Sun Rider's abilities from this class. As an elemental creature, the Fiery Steed does not need to eat, drink, or breathe. As the Sun Rider grows in level, his or her Fiery Steed gains increases to its natural armor bonus to AC, as well as increases to all of its ability scores and to its hit dice. The Fiery Steed receives all associated benefits for these increases, such as gaining Damage Reduction from the fire-element template at 8 hit dice, gaining increases to its burn DC and damage, extra skill points with each hit die, increased base saving throws, new feats, and so on.
Fiery Steed Advancement
Sun Rider...............Total Increases..............................Total
Level.........Natural Armor....Str..Dex..Con..Int..Wis..Cha...Hit Dice
1-3...............+1...............+1...+1...+1...+1...+1...+1......7 HD
4-6...............+2...............+2...+2...+2...+2...+2...+2......8 HD
7-9...............+3...............+3...+3...+3...+3...+3...+3......9 HD
10................+4................+4...+4...+4...+4...+4...+4.....10 HD
Example Fiery Steed
Cinderflare, Fire-Element Griffon, Sun Rider Fiery Steed
Large Elemental (Fire) (Extraplanar) (Augmented, inherited template)
HD/HP: 7d8+28 (SRL 1-3); 8d8+31 (SRL 4-6); 9d8+43 (SRL 7-9); 10d8+46 (SRL 10)
Initiative: +3 (SRL 1-3); +3 (SRL 4-6); +4 (SRL 7-9); +4 (SRL 10)
Speed: 30 ft., fly 80 ft. (average maneuverability)
AC: 19 (SRL 1-3); 20 (SRL 4-6); 22 (SRL 7-9); 23 (SRL 10)
Base Attack/Grapple: +5/+13 (+6/+15 instead at SRL 4-6 and SRL 7-9, +7/+17 instead at SRL 10)
Attack: Bite +9 melee (2d6+4 plus 1d4 fire) (SRL 1-3); bite +11 melee (2d6+5 plus 1d6 fire) (SRL 4-6 and SRL 7-9); bite +13 melee (2d6+6 plus 1d6 fire) (SRL 10)
Full Attack: Bite +9 melee (2d6+4 plus 1d4 fire) and 2 claws +6 melee (1d4+2 plus 1d4 fire) (SRL 1-3); bite +11 melee (2d6+5 plus 1d6 fire) and 2 claws +8 melee (1d4+2 plus 1d6 fire) (SRL 4-6 and SRL 7-9); bite +13 melee (2d6+6 plus 1d6 fire) and 2 claws +10 melee (1d4+3 plus 1d6 fire) (SRL 10)
Space/Reach: 10 ft./5 ft.
Special Attacks: Pounce, rake 1d6+2 (1d6+3 instead at SRL 10), burn DC 14 (15 instead at SRL 4-6, 16 instead at SRL 7-9, 17 instead at SRL 10)
Special Qualities: Darkvision 60 ft., scent, elemental traits, immunity to fire, vulnerable to cold, fiery steed traits, empathic link, share saving throws, damage reduction 5/- (damage reduction only gained at SRL 4-6, SRL 7-9, and SRL 10)
Saves: Fort +5, Ref +8, Will +6 (SRL 1-3); Fort +5, Ref +9, Will +6 (SRL 4-6);
Fort +7, Ref +10, Will +8 (SRL 7-9); Fort +7, Ref +11, Will +8 (SRL 10)
Abilities: Str 19, Dex 16, Con 16, Int 6, Wis 14, Cha 9 (SRL 1-3);
Str 20, Dex 17, Con 17, Int 7, Wis 15, Cha 10 (SRL 4-6);
Str 21, Dex 18, Con 18, Int 8, Wis 16, Cha 11 (SRL 7-9);
Str 22, Dex 19, Con 19, Int 9, Wis 17, Cha 12 (SRL 10)
Skills: Jump +8, Listen +7, Spot +11 (SRL 1-3); Jump +9, Listen +8, Spot +11 (SRL 4-6); Jump +9, Listen +9, Spot +13 (SRL 7-9); Jump +10, Listen +9, Spot +14 (SRL 10)
Feats: Iron Will, Multiattack, Weapon Focus (bite) (SR 1-3 and SRL 4-6); Iron Will, Multiattack, Weapon Focus (bite), Fly-By Attack (SRL 7-9 and SRL 10)
Alignment: Usually neutral
Challenge Rating: 5 (SRL 1-3); 6 (SRL 4-6, SRL 7-9, SRL 10)
Burn (Ex): As per the ability of Fire Elementals, except DC is 7 + hit dice, and damage is 1d4 at 7 hit dice or 1d6 at 8-10 hit dice.
Edit: I revised the descriptions, and will add some background material flavor text later. I adapted the fire element template's damage reduction for 8+ hit dice from 5/+1 to 5/- in keeping with the change in fire elementals with 3.5, but that's the only thing about the fire element template that would change under 3.5 rules (at least, in a direct conversion) besides the addition of Extraplanar subtype due to fire element creatures originating on the Elemental Plane of Fire, and the Augmented subtype due to fire element creature being a template. I felt that giving the class 4 skill points per level would make it a bit overpowered in total, and as it is now it may still be a bit powerful, but focused.
