Two systems, two combatants who fight as one. The numbers below are for players and DMs, everyone else will have a better time on her main page.
Fighter 17. Human, Lawful Good, Deity Bahamut.
32-point buy, plus level bumps at 4th/8th/12th/16th, plus gear enhancement, total score shown includes both.
Attack: +26/+21/+16/+11 (+17 BAB + 3 Str + 5 Enhancement + 1 Weapon Focus). Damage: 1d8+8, plus 2d6 vs. Evil (×3 crit, 19–20/×3 with Improved Critical).
Damage: 3d8+24, plus 2d6 vs. Evil.
Attack: +23/+18/+13/+8. Damage: 1d8+6 (19–20/×2).
Level 17 wealth, roughly 340,000 gp equivalent.
General, Fighter, built specifically for a partnership like this one.
Ride 8 ranks, Mounted Combat, Handle Animal 4 ranks.
You take no penalty for riding a dragon without an exotic saddle, and gain a +4 competence bonus on all Ride checks while mounted on a dragon. Additionally, once per round when your dragon mount is targeted by an effect requiring a Reflex save, you may attempt a Ride check as an immediate action; if your check result exceeds the save DC, your dragon succeeds on its Reflex save.
Hybrid green/gold dragon. Large, Lawful Good.
+19 melee, 2d6+6
+14 melee, 1d8+3 each
+14 melee, 1d6+3 each
+14 melee, 1d8+9
Once every 1d4 rounds, Gilt chooses one of two 40-foot cone effects:
10d6 acid damage, Reflex DC 21 half.
10d6 fire damage, Reflex DC 21 half.
Water Breathing, Darkvision 120 ft., Low-Light Vision, Blindsense 60 ft., Spell Resistance 19.
Sophia wields her +5 Holy Dragon-Lance from Gilt's back. With Spirited Charge, a mounted charge deals triple damage (3d8+24, plus 2d6 vs. Evil), while Gilt executes a Flyby Attack or full aerial dive to set it up.
Using the Dragon Rider feat, Sophia can substitute her Ride check (+34) for Gilt's Reflex save once per round, practically guaranteeing he avoids area-of-effect spells like Fireball or Lightning Bolt outright.
A 2024-rules conversion, built as an actual playable character rather than a monster block.
Human, Fighter 18 (Cavalier) · Lawful Good · Proficiency Bonus +6
5e ability scores cap at 20 outside exotic magic. DEX and CHA shown here are the item-boosted totals, taken as the practical ceiling rather than 3.5e's uncapped +6/+7 gear bonuses.
Advantage on saves to avoid falling off Gilt, and landing safely from a mount-related fall costs no movement.
When Sophia hits a creature with a melee attack, she can mark it, marked creatures have disadvantage on attacks against anyone but her, and she gets a bonus attack against them if they attack someone else anyway.
When Gilt is hit by an attack or fails a Dexterity save while Sophia is mounted on him, she can expend a superiority-style die as a reaction to add to his AC or Dex save, potentially turning a hit into a miss, the direct translation of the Dragon Rider feat's reflex-save assist.
Sophia makes three attacks with her lance.
Melee Weapon Attack: +11 to hit, reach 10 ft. (mounted). Hit: 13 (1d12+6) piercing plus 7 (2d6) radiant damage against fiends and undead.
If Gilt moved at least 20 feet straight toward the target this turn, the lance attack deals an extra 18 (4d8) damage.
Large Dragon (hybrid green/gold ancestry), Lawful Good. CR 15 (13,000 XP)
Gilt makes three attacks: one bite and two claws.
Melee Weapon Attack: +11 to hit, reach 10 ft. Hit: 17 (2d10+6) piercing damage.
Melee Weapon Attack: +11 to hit, reach 5 ft. Hit: 13 (2d6+6) slashing damage.
Gilt exhales acid or fire in a 60-foot line (5 feet wide), his choice. Each creature in the line makes a DC 18 Dexterity saving throw, taking 55 (10d10) acid or fire damage on a failure, or half as much on a success.