The Great Wyrm

This is from MR. Rhexx's book, "What They Don't Tell You About Dragon Hoards."

You should pick it up! Its awesome!

Draconic Assimilation

Draconic Assimilation 1st-level Great Wyrm feature Your Strength score increases by 2, to a maximum of 20. The ritualistic imbibing of the draconic blood instills in you the features and abilities of your master. When a spellcasting feature lets you learn or replace a warlock cantrip or a warlock spell of 1st level or higher, you can choose the new spell from the sorcerer spell list or the warlock spell list. You must otherwise obey all the restrictions for selecting the spell, and it becomes a warlock spell for you. In addition, the nature of your draconic patron (its color and type) influences features that you gain at this level and features that are obtained later.

Great Wyrm Color      Damage Type             Feature                     Breath Weapon
Black                            Acid                              Water Breathing     5 by 30 ft. line (Dex.save)
Blue                              Lightning                     Sound Mimicry       5 by 30 ft. line (Dex.save)
Brass                           Fire                               Animal Language    5 by 30 ft. line (Dex.save)
Bronze                         Lightning                     Cloud Sight              5 by 30 ft. line (Dex.save)
Copper                         Acid                             Athletic Might          5 by 30 ft. line (Dex.save)
Gold                             Fire                               Dream Seer              5 by 30 ft. line (Dex.save)
Green                           Poison                        Green Tongued          15 ft. cone (Con.save)
Red                              Fire                              Golden Sight              15 ft. cone (Dex.save)
Silver                           Cold                            Cloud Walk                 15 ft. cone (Con.save)
White                          Cold                             Ice Walk                     15 ft. cone (Con.save)

You gain resistance to the damage type associated with your Patron. You also obtain its special feature as described on the dragon chart.

Water Breathing: You can breathe both water and air.

Sound Mimicry: You can mimic sounds you have heard, including voices. A creature that hears the sounds you make can tell they are imitations with a successful Wisdom (Insight) check opposed by your Charisma (Deception) check.

Animal Language: You can comprehend and verbally communicate with beasts.

Cloud Sight: You can see through any kind of natural or magical fog, smoke, cloud or gas.

Athletic Might: You do Acrobatic checks with advantage and your jumping distance is tripled.

Dream Seer: Once a day, you may fall into a trance and enter the dreams of a sleeping creature within 5 feet of you. While within, you can see what the creature is currently dreaming about and may converse with the creature from within. The creature is perfectly lucid and to them, the dream becomes extraordinarily vivid. Further it will remember all that transpired upon waking.

Green Tongued: You gain a +2 to your Persuasion, Deception, and Intimidation checks.

Golden Sight: You gain advantage in Perception and Investigation checks made to find hidden treasure, whether inside hidden compartments or hidden walls. Further you can perfectly count and always know the exact value of a pile of treasure.

Cloud Walk: You have the ability to walk on gaseous substances at will, including clouds.

Ice Walk: Difficult terrain originating from snow, ice, or any kind of slippery surface does not affect you.

Black

Black dragon

Silver

Cold resistance

The Golden Trade

Your master thirsts for coin and treasure. It has blessed you with great power and the time to pay it back is now.

Your patron grants you access to the ritual of the golden trade. The ritual lasts for 8 hours, where the warlock draws draconic runes of transportation around treasure it may seek to send its master. During the last hour of the ritual, a telepathic connection is formed between the warlock and the Patron; used to discuss the nature of the trade.

In exchange for treasure, the Great Wyrm offers access to its vast limitless hoard. As part of the ritual, the warlock may “tribute” its master with treasure in the form of coins, gems and art objects. Each individual piece of art must not weigh more than 500lbs for it to be eligible for the golden trade.

Upon receiving its tribute, the Great Wyrm grants its servant access to magical weapons and armor from its hoard; which the warlock may take depending on the amount tributed. Anything taken from the great hoard is considered merely borrowed, and the Great Wyrm expects the magical item to be returned upon expiration of the time limit associated with the rarity of the item. Each item borrowed in this fashion is enchanted via a powerful contract signed in blood by both parties during the ritual of the golden trade. If the warlock dies or refuses to pay the golden tax, which equals 20% of the value of all items borrowed at the end of the contract’s expiration; then the magical item in question automatically teleports back into the Great Wyrm’s hoard. Paying the golden tax allows the warlock to keep the item for another contract term. As long as the warlock does not break any of the above mentioned rules, the Great Wyrm may not forcibly recall or ask for the magical item back.

Magical Item     Tribute needed   Contract Expiration
Uncommon        500gp                   10 years
Rare                     5,000gp                 5 years
Very Rare            30,000gp               1 year
Legendary          150,000gp            1 month

Draconic ability

The ability, removing it from being tied to the dragon type

Golden Sight

You gain advantage in Perception and Investigation checks made to find hidden treasure, whether inside hidden compartments or hidden walls. Further you can perfectly count and always know the exact value of a pile of treasure.

Dragon Apotheosis

Now that your body has acclimated to the Great Wyrm’s blood, it is time for your master to bequeath you the power of dragons. A secret ritual involving bathing in dragon’s blood has transformed your body into a Half Dragon. Your creature type is now Dragon, in addition to any other creature type you possess.

Your Strength score increases by 4 to a maximum of 24. Your Constitution and Charisma scores increase by 2 to a maximum of 22. You gain expertise in Athletics. You obtain Blindsight at a range of 30ft and Darkvision at a range of 60ft. You become immune to magical sleep.

Your skin transforms into the scaly leather of dragonkind. Your AC can’t be less than 17, regardless of what kind of armor you are wearing. Additionally your new draconic maw becomes a natural weapon for you, which you can use to make unarmed strikes. If you hit with it, you deal piercing damage equal to 1d10 + your Strength modifier plus 1d4 damage of the energy type associated with your Patron. You may only use this attack once per round.

You obtain the ability to breathe energy from your mouth like a dragon, it’s form and effect dependent on the nature of the Great Wyrm. Use the graph under the class feature Draconic Assimilation for the shape of the breath and the saving throw required. All saving throws halve damage on a success. The damage for your breath weapon is 4d10 of the corresponding element. Further, your Breath Weapon gains Recharge 6 (at the beginning of your turn roll a d6, on a roll of 6 you regain usage of your breath weapon). The DC for your breath weapon equals 8+ your proficiency modifier + your constitution modifier

Zenith of Evolution

Your draconic journey has reached its peak and you no longer require the Great Wyrm’s blood. The end path is here. Glory is within reach.

Your blood is magic. All your spells are now cast without the need for any somatic or verbal components.

Your body is perfect. You grow draconic wings on your back, which grant you a flying speed of 60ft.

Your mind is infallible. You gain a feature called Legendary Resistance. If you fail a saving throw, you can choose to succeed instead. You regain usage of this feature on a long rest.

You are complete. You become immune to the energy type associated with your Patron.