While some warlocks are content to throw their lot in with any old Fiend, you chose to sell yourself to an entity at least five times more powerful than they are. How you were able to swear yourself into the service of Tiamat, Queen of all Chromatic Dragons, is for you to decide. What is not for you to decide is your loyalty to her, which is unwavering and uncompromising. For your subservience, she is prepared to grant you power only known to the most ancient of her children. Are you cunning enough to wield it?

Draconic Transformation

At 1st level, your skin begins to harden and take on a shimmering, dragon-scale-like appearance. These scales change to the following colors that correspond to spells you cast that deal acid, cold, fire, lightning, or poison damage:

• Acid – Black
• Cold – White
• Fire – Red
• Lightning – Blue
• Poison – Green

Furthermore, whenever you cast Eldritch Blast or use a breath weapon or breath spell (such as Dragon's Breath), you can change the damage type of each individual blast between fire, acid, poison, cold, and lightning.

You can spend one minute to mentally rearrange the colors of your scales however you wish. In addition, you add your Charisma modifier to your Unarmored AC.

Furthermore, your body grows draconic features: claws, and your choice of a tail that can fell opponents or a draconic maw that delivers an elemental-infused bite. No matter which you choose, they are considered natural weapons with which you are proficient. You can add your Charisma modifier to the attack rolls of these natural weapons instead of your Strength modifier. At 6th level, these natural weapons become magical for the sake of overcoming resistance.

Your claws deal 1d4 slashing damage. You can make one claw attack as an action, and one claw attack as a bonus action if you used the Attack action on the same turn. The damage for your claws increases to 2d4 at 5th level, 3d4 at 10th level, and 4d4 at 14th level.

Your tail deals 1d6 bludgeoning damage. On a hit, if the target is of one size category larger than you are (or any size smaller), they must make a Constitution saving throw equal to your spell save DC. If they fail, are knocked prone. The damage for your tail increases to 2d6 at 5th level, and 3d6 at 10th level, and 4d6 at 14th level.

If you choose the bite attack, your physical appearance doesn't change until you make the attack. Then it contorts to that of a chromatic draconic humanoid, your jaws enlarging and teeth lengthening and sharpening. The bite deals 1d10 piercing damage, plus 1d6 of acid, cold, fire, lightning or poison damage (your choice). Your dragon scales match the type of damage dealt. The elemental damage for your bite attack increases to 2d6 at 5th level, 3d6 at 10th level, and 4d6 at 14th level.

Expanded Spell List

As part of your pact, the following spells are added to your spell list, and are always prepared:

1st Level: Absorb Elements, Chromatic Orb

2nd Level: Dragon's Breath, Scorching Ray

3rd Level: Fireball, Lightning Bolt

4th Level: Polymorph, Vitriolic Sphere

5th Level: Cloudkill, Cone of Cold

Unleash Draconic Aspect

At 6th level, you may use your bonus action to unleash your Draconic Aspect for 1 minute, transforming into a raging chromatic dragonkin. While in this state, whenever you cast any non-spell-attack spell or cantrip that would deal acid, cold, fire, lightning or poison damage, you can change the damage type of that spell to any of the other aforementioned types. Spells that deal these damage types also deal two extra damage dice and have their area of effect changed to a 20-foot-cone originating from your mouth. If the spell's area of effect is already a cone, the cone's size does not change. You may use this feature a number of times equal to your Charisma modifier (minimum of one) per long rest. While in this state, you can use a bonus action to make all creatures of your choice within 10 feet of you take 2d4 acid, cold, fire, lightning or poison damage (your choice). 

Hoard of the Chromatic Queen's Chosen

At 10th level, you lose the ability to gain Temporary Hit Points, and any Temporary Hit Points you have when reaching this class level are lost. Instead, the Queen of Evil Dragons extends to you the secret to every evil dragon’s longevity and power: Its hoard.

For every 2,000 gp worth of magic items, precious gems, stones, and money in your possession, you gain 1 Temporary Hit Point. This counts retroactively for any monetary value on your person (bags of holding and other personal extradimensional items and their contents count towards this value) at the time you gain this feature, and you gain one more Temporary Hit Point per 2,000 gold worth of magic items going forward. You cannot gain Temporary Hit Points through any method other than this feature, and Temporary Hit Points gained through this feature persist through long rests.

If any of this value is ever removed from your possession, you lose Temporary Hit Points equal to its value, divided by 2,000 (round down and ignore any remainders, minimum of 1 temporary hit point lost per transaction [or theft]). If this value is greater than the sum of your current Temporary Hit Points, any extra is deducted directly from your hit points as force damage that cannot be resisted or negated. If you are reduced to 0 hit points from this effect, you are not knocked unconscious. Instead, you enter into a dormant catatonic state with one hit point and cannot be awakened or regain hit points until you are presented with 2,000 gold pieces worth of treasure. When that happens, you gain 1 hit point and can regain hit points as normal. You do not need to make death saving throws while in this state.

Champion of Tiamat

At 14th level, your unarmored AC is now equal to 13 plus your Charisma modifier. Your Hoard of the Chromatic Queen’s Chosen feature now extends to real estate properties, businesses, land, and items in demiplanes not connected by bags of holding and the like.

You also gain these additional benefits when using your Unleash Draconic Aspect feature:

• You gain a flying speed of 60 feet.
• You become resistant to acid, cold, fire, lightning, and poison damage.
• If you fail a saving throw, you can choose to succeed instead. You can only use this feature once per long rest.
• Spells of 2nd level or lower have no effect on you unless you want them to.
• Your 30-foot cone area of effect for spells extends to a 40-foot cone.