Can the half-dragon template have a negative impact on fly speed?

First example: A half-dragon astral deva. Astral devas normally have wings, but they’re Medium, and the Half-Dragon template states that Medium half-dragons don’t have wings. Does the Astral deva lose its wings due to the template?

Second example: A half-dragon solar. Solars have a land speed of 50 ft., and a fly speed of 150 ft. The Half-Dragon template states that a creature of this size can fly at twice its base land speed, with a maximum of 120 ft. Does the solar have its fly speed reduced to double its land speed (100 ft.), or to the Half-Dragon template’s maximum fly speed (120 ft.), or does it keep its base fly speed (150 ft.)? Similarly, what (if anything) happens to its maneuverability?

Third example, based on the maneuverability part of the previous point: a half-dragon great wyrm (or any creature with a fly speed greater than 120 ft. but worse than the average maneuverability given by the Half-Dragon template). Does it keep the best aspects of its flight sources, or the worst aspects, or does it take one source for its wings in its entirety?

I’m a quarter Draconian, a quarter Dragonborn and half Half-Dragon?

What are the differences between “Dragonborn”, “Half-Dragon”, and “Draconian” races in D&D?

In the Hoard of the Dragon Queen adventure, for example there is a Half-Dragon npc. I had assumed that when writing the adventure they were only allowed to use known material from Basic, and so renamed the Dragonborn into “Half-Dragon” for the sake of compatibility etc. However, the dragon breath rules are not at all similar for the half-dragon and the dragonborn, and I’ve also noticed wiki article that imply that they are different races entirely. (Thus introducing me to the term Draconian)

Are there clear differences between these three races, (in the same way there are differences between Goblins and Hobgoblins, or Dragonborn and Lizardfolk and Kobolds,) or are they really just three different setting names for the same basic race?

Answers can either be D&D 5e specific, or be based on the lore from all editions of Dungeons and Dragons. (I’m assuming here that the answer will be the same regardless)

Here are two images, the first one is a “half-dragon” from the front of the Hoard of the Dragon queen module, and the second one is a “dragonborn” from the 5e player’s Handbook. I’ve included these images to help explain my confusion.

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Half-Dragon using Disguise self, how does it work?

So, from my understanding, a half-dragon cannot use disguise self to appear human. There’s just too many limbs for that to work properly, not to mention technically the dragon is no longer humanoid in type and therefor cannot be changed to a humanoid sub-type.

You cannot change your creature type (although you can appear as another subtype)

Creature type changes to dragon. Do not recalculate hit dice, base attack bonus, or saving throws.

My question is, can disguise self allow a half-dragon to appear as another medium sized dragon, or a wyvaran, or a drake, or anything similar of the dragon type?

Is this Half-dragon Quaggoth mage boss balanced? Revised version

This is going to be the first boss for my upcoming campaign. I have 7 5th level players, and this fight is meant to challenge them quite a bit. There will also be a down leveled mage (Challenge rating 4) and at least 2 regular quagoths.

The story is that this quagoth found a dying dryad and consumed her heart, this made him a sorcerer as well as giving him some druid magic. Then the cult of the dragon found him and made him a half dragon. If the players don’t kill him I plan on making him an NPC later on.

I would like to know if this monster is ready to be thrown at my players. If it is too overpowered or underpowered at its current challenge rating. And what I can do to fix any balancing problems found in the stats of this monster.

Treill

Half-dragon Quaggoth Thonot (5th level sorcerer)

Armor Class: 18 (permanent Barkskin, Dragonic resilience, ring of protection)

Hit points: 70 (10d8+3)

Str (16; +3) Dex (12; +1) Con (16; +3) Int (8; -1) Wis (16; +3) Cha (16; +3)

Saving Throws: Str +6, Con +6

Senses: Treill has blindsight out to 10 ft, and darkvision out to 180 ft.

Challenge: 7

Wounded Fury. While he has 20 hit points or fewer, Treill has advantage on attack rolls. In addition, he deals an extra 7 (2d6) damage to any target he hits with a melee attack.

Lighting resistance.

Meta magic. 5 sorcery points:

Twined spell, distant spell.

Multiattack. The quaggoth makes two claw attacks.

Claw Attack. Melee Weapon Attack: + 5 to hit, reach 5 ft., 1 target. Hit: 10 (2d6 + 3) slashing damage, puls 4 (1d8) fire damge, and 7 (1d8+3) fire damge to second target. (Only one calaw attack per turn may use green flame balde).

Lighting breath Recharge (5-6). Treill can use his action to exhale destructive energy. Each creature in a 5 by 30 ft. line must make a Dexterity saving throw or take 24 (7d6) lighting damage, or half as much on a successful save.

Spellcasting. Treill is a 5th level caster, his casting ability is Charisma. DC 14, +6 to hit with spell attacks.

Cantrips (at will) firebolt, sword burst, poison spray, predestination, Toll the Dead, Green flame blade.

1st level (4 slots): Cormatic orb, magic missile, shield.

2nd level (3 slots): Invisibility, spider climb.

3rd level (2 slots) Lighting bolt, Hast.

Innate spellcasting Thonot DC 14. +6 to hit.

At will : Mage hand, Feather fall.

1/day Cure wounds, enlarge/reduce, heat metal, mirror image.

Magic initiate (druid) DC 14, +6 to hit with spell attacks.

Cantrips: Thorn whip, druidcraft

1/day: healing word