How can my half-dragon villain aim to become more draconic?

Question

The villain in the adventure I'm currently running is a half-dragon druid. Their motivation is that they want to claim some of the power and glory of their draconic ancestors. At the moment, I'm just making something up, but do any rules exist that allow for an NPC to become 'more draconic'?

Answer 1

Beyond simply wishing, polymorphing at a high level, there are some baby steps...

You're the DM, so anything is possible. But if you're looking for something that fully fits in the game's mechanics, this Unearthed Arcana specifically mentions three new feats that let a Dragonborn be, well, more draconic

If this is the sort of villain that 'grows with the party' these could make stepping stones to potentially wishing/polymorphing to be a full dragon

Dragon Fear

Prerequisite: Dragonborn
When angered, you radiate menace. You gain the following benefits:

• Increase your Strength or Charisma score by 1, up to a maximum of 20.
• Instead of exhaling destructive energy, you can roar and expend a use of your breath weapon to force each creature of your choice within 30 feet of you to make a Wisdom saving throw (DC 8 + your proficiency bonus + your Charisma modifier). A target automatically succeeds if it can’t hear or see you. On a failed save, a target becomes frightened for 1 minute. If the frightened target takes any damage, it can repeat the saving throw, ending the effect on itself on a success.

Dragon Hide

Prerequisite: Dragonborn
You inherited the might and majesty of your dragon ancestors. You gain the following benefits:

• Increase your Strength or Charisma score by 1, up to a maximum of 20.
• You grow retractable claws from the tips of your fingers. Extending or retracting the claws requires no action. The claws are natural weapons, which you can use to make unarmed strikes. If you hit with them, you deal slashing damage equal to 1d4 + your Strength modifier, instead of the bludgeoning damage normal for an unarmed strike.
• Your scales harden; you gain a +1 bonus to AC while you aren’t wearing armor.

Dragon Wings

Prerequisite: Dragonborn
You sprout draconic wings. With your wings, you have a flying speed of 20 feet if you aren’t wearing heavy armor and aren’t exceeding your carrying capacity.

All of these give a plausible path to your villain becoming increasingly more draconic as they gain in power.

Answer 2

If they can cast True Polymorph ...

... they can become an Adult dragon.

If you look at the Arch Mage in the Monster Manual - a CR 12 NPC/Monster - that character can cast level 9 spells. As you build this NPC, work through the DMG NPC section (Chapter 4, Designing NPC's) and set him up similarly.

There is a Druid NPC (ArchDruid, CR 12, Volo's Guide to Monsters) that can cast 9th level spells as well. This is another template that you can adapt your NPC to, and it is one that looks like it will fit your half-dragon druid better.

Spellcasting: The Archdruid is an 18th-level spellcaster. Its Spellcasting Ability is Wisdom (spell save DC 17, +9 to hit with spell attacks). It has the following Druid Spells prepared:

• Cantrips {snip} • 9th level (1 slot): Foresight

Substitute in True Polymorph for Foresight and you are good to go. Can you do that? Besides "Yes, you are the DM" the MM has this to say about spell casting NPCs:

The monster has a list of spells known or prepared from a particular class. The list might also include spells from a feature in that class, such as the Divine Domain feature of the cleric or the Druid Circle feature of the druid. {snip} You can change the spells that a monster knows or has prepared, replacing any spell on a monster’s spell list with a different spell of the same level and from the same class list. If you do so, you might cause the monster to be a greater or lesser threat than suggested by its challenge rating. (MM, Introduction, Spellcasting)

If you think that True Polymorph would bump the CR from 12 - 13, go ahead and do that. 9th level spells are already quite powerful but some are more powerful than others.

Answer 3

One thing that the villain might choose, even at quite low levels, is concentrating on spells and magical items that allow your druid to emulate draconic powers or other traits, and particularly those of the right bloodline.

Regardless of bloodline, the druid might seek out things that allow flight, for instance, and start hoarding treasure. Recruiting kobold minions would also be typically draconic.

If the druid is half black dragon, a preference for attack spells doing acid damage, an ability to breathe underwater, and a lair in the swamp would all fit.