Dragon Knight
While using heavy armor, a dragon knight is extraordinarily resilient. Any slashing, piercing and bludgeoning damage they take is reduced by 5. This reduction is applied before any eventual resistances, and does not stack with other sources of damage reduction (such as the Heavy Armor Master feat).

Fire Affinity
When casting spells that deal fire damage, the scion deals an additional 3 points of damage (accounted for in the Green-flame Blade attack action).

Metamagic
The flame scion has access to the following metamagic options: Quicken Spell, Subtle Spell. These have 3 uses each.

Spellcasting
The flame scion casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 15, +7 to hit with spell attacks):

Cantrips (at will): Green-Flame Blade, Shocking Grasp, Fire Bolt

3/day each: Ashardalon's Stride, Absorb Elements, Sleep (4th level, 11d8)

2/day each: Dimension Door, Fireball, Counterspell, Dispel Magic

1/day each: Summon Draconic Spirit (6th level), Globe of Invulnerability

Cast a spell
The scion can cast a spell as its main action, leaving its bonus action for a quickened cantrip.

Attack
The flame scion wields a Greatsword +1. He can either attack using the Green-flame Blade cantrip (with its 2d8+3 additional damage), or perform a regular attack with a combat maneuver.

Greatsword +1
Melee Weapon Attack: +8 to hit, 2d6+4 slashing damage.

Pushing Attack
Melee Weapon Attack: +8 to hit, 3d6+4 slashing damage. If the attack hits, the target has to succeed a DC 15 strength saving throw or be pushed 15ft away from the scion.

Disarming Strike
Melee Weapon Attack: +8 to hit, 3d6+4 slashing damage. If the attack hits, the target has to succeed a DC 15 strength saving throw or be disarmed.

Cast a spell
The scion can either cast a spell that requires a bonus action (such as Ashardalon's Stride), or quicken a regular spell or cantrip.

Counterspell
The scion can cast Counterspell as a reaction.

Absorb Elements
The scion can cast Absorb Elements as a reaction.

Attack of Opportunity
Melee Weapon Attack: +8 to hit, 2d6+4 slashing damage.