I review each (currently available) dragon, comparing it with its skill mates, and general utility. A reminder that these are my opinions, and they are formed with a high difficulty level in mind, where said skill is advantageous.
Other posts:
1: General considerations
2: Healing, Paralysis
4: Focus, Ice
5: Poison
6: Electric, Sonic, Rock
7: Gas, Razor, Wild
8: Top Ten
Change log:
- July 2020: added Galeslash
Agile 
[]
At the moment, we never had Healing enemies in DT, so while these dragons have no advantage in any level right now, they still have general utility.
Max stats of the currently available dragons. In bold: starter dragon.
| Dragon | Atk | Fpr | Mov | Crit | Hpr | Def | Health |
|---|---|---|---|---|---|---|---|
| Deathly Galeslash | 275 | 415 | 3 | 150 | 250 | 100 | 2300 |
| Gronckle | 200 | 355 | 3 | 150 | 250 | 60 | 4600 |
| Hobgobbler Smitten Hobgobbler |
300 | 285 | 3 | 150
50 |
300 | 125
0 |
2850 |
| Light Fury | 375 | 335 | 4 | 150 | 400 | 250 | 2750 |
| Raincutter | 300 | 300 | 3 | 150 | 350 | 175 | 3350 |
| Smothering Smokebreath | 275 | 350 | 3 | 150 | 500 | 187.5 | 2150 |
| Stormcutter | 300 | 395 | 3 | 150 | 450 | 137.5 | 2600 |
Deathly Galeslash[]
With the highest damage for the Agile class on both first and second attacks (830+ ~400 burn on first and 1763 on second) this recent addition to the game makes for a fun member to your DT roster. The third skill that enhance its speed coupled with its long range attacks means that on turn 2 it can hypothetically reach any enemy on the field and help speed up enemy fights. It has then a cool niche in clearing up fast low-ish levels when both your viking and your dragon can 1-hit ko any enemy, and the only issue is having to reach the enemy to defeat them. The only drawbacks are the low health (that shouldn't matter much for the strategy above) and the lack of interesting effects like multi-range attacks and stuns. But that would probably make it too op.
| 1st | 2x FPR | long | burn ~1x FPR for 2t | |
|---|---|---|---|---|
| 2nd | 4.25x ATK | long | 4 cd | |
| 3rd | speed, +20% dodge | self | 8 cd | for 3t |
Pros:
- High FPR
- Two long range attacks
- Increase speed
Cons:
- Low HP
Rating: 
Fast, strong sniper.
Gronckle[]
Faithful to its Boulder class, this armored dragon shows an impressive health pool. To balance that, their dodge rate is low, but it shouldn't affect it much. It has a nice first attack, thanks to its high FPR and mid range; due to its 5x multiplier, the second attack still do damage, even with the lowest ATK value for Agile dragons, but has a close range. As a nice addition, it has a sure stun on the enemy, and a rather low cooldown. Its third action is not so relevant for a tanky dragon like this.
| 1st | 2x FPR | mid | ||
|---|---|---|---|---|
| 2nd | 5x ATK | close | 4 cd | stun |
| 3rd | dodge, heal | self | 8 cd |
Pros:
- High HP
- Sure stun on second attack
- Powerful first attack
- Easy to obtain
Cons:
- Second attack per se is not that strong
- Third action is not the best
Rating: 
Being a starter dragon, or one that can purchase for 
(once one met the UDT points requirements), it's a good dragon for DT.
Hobgobbler[]
Both Smitten and regular Hobgobbler have the same actions and most of the stats. They only differ in critical chance and dodge rate, that are way worse in the "free" Smitten Hobgobbler. However the regular Hobgobbler is one of the most expensive dragons, so the same rating applies to both. Both attacks are average in term of damage, and the biggest drawback is that they are only close range. Incoming damage will be inevitable, and it's just a bit mitigated by their healing third action. The only positive aspect is that their second attack is multi range with only 3 turns cooldown.
| 1st | 2x ATK | close | ||
|---|---|---|---|---|
| 2nd | 3x FPR | close | 3 cd | multi |
| 3rd | heal | self | 8 cd |
Pros:
- Smitten is free with the expansion
- Second attack is multi range with low cooldown
Cons:
- Regular Hobgobbler is expensive
- Smitten Hobgobbler has the worst crit chance and won't dodge, never.
- All attacks are close range
Rating: 
I think they are expensive for what they have to offer.
Light Fury[]
Someone please explain to me why she has a higher ATK than FPR, but her attacks are based on FPR only? Anyway, she hits hard. She has the strongest first attack among Agile dragons, and her second attack is only second to the Stormcutter. even taking into account the extra damage (about 10% of the attack damage). Both are mid range too, so quite versatile. And the second one has a cooldown of only 3. She's also the fastest agile dragons (but that is not at the top of my list of useful things). Secondary effects are not really relevant, the burn effect is nice but not that strong. She's quite fragile as for Hp, so her third action can help her avoid some hit. Her dodge rate is high anyway. The really drawback is that she's meber only, so behind a paywall.
| 1st | 2.25x FPR | mid | lower enemy str | |
|---|---|---|---|---|
| 2nd | 4.25x FPR | mid | 3 cd | burn (10% FPR) |
| 3rd | dodge | self | 8 cd |
Pros:
- Hits hard
- Good natural dodge, and a way to increase it
- Low cooldown on second attack
Cons:
- Behind a paywall
- Behind a paywall
- Behind a paywall
- Might be a bit fragile
- Lackluster secondary effects, but you don't need it if you hit hard enough
Rating: 
Would be higher if she was not member only. She's also great for racing. Smells like p2w.
Raincutter[]
All close range attacks, no multi range, no secondary effects. A third action that enhance only the second attack for 3 turns, but said attack has a cooldown of 3 turns, so it's used once. And it has a cooldown of 4 turns, so they can't even synchronize. While the first attack is on the weak side (same as Hobgobbler and Stormcutter), the second one, especially Charged up, can deal a good amount of damage. But it has nothing else to offer. It's a bit tanky though.
| 1st | 2x ATK | close | |
|---|---|---|---|
| 2nd | 4.25x FPR | close | 3 cd |
| 3rd | up FPR 50% | self | 4 cd |
Pros:
- Powerful second attack with low cooldown
- Third action strenghted further its second attack
- High Hp, but the gronckle can do better
Cons:
- Everything is close range
- No other effects
- Bad synchronization between third action and second attack
Rating: 
Meh. A burst of nearly 2k damage every 4 turns sounds nice, but its kit is so poorly put together. Such a pity.
Smothering Smokebreath[]
Three attacks? Two of which multi range? I'm sold. I don't think I need to tell more. Ok, multi range attacks are close range, but still you have the first one that is mid range. Low cooldown on second one. Damage is good on all three. It has quite a low Hp, and the high dodge rate can help to a point. Protect this little buddy.
| 1st | 2x FPR | mid | ||
|---|---|---|---|---|
| 2nd | 4.25x ATK | close | 3 cd | multi (front) |
| 3rd | 4x FPR | close | 4 cd | multi (all) |
Pros:
- 3 attacks with good damage
- 2 attacks are multi range
- High dodge rate, might hep with its fragility.
Cons:
- Multi range attacks are close range
- Fragile
Rating:
My choice for the Agile skill
Stormcutter[]
Finally a long range attack. With a low cooldown, massive damage output, + additional strong damage for 2 turns, it's impressive, dealing over 2.4k damage in 2 turns at level 50. But that's it. First attack is close range, and on the weak side. Self healing can help in difficult situations (self heal for 2/3 of the health), as it is quite low in Hp, but with that long cooldown you'll probaably use it once in a level.
| 1st | 2x ATK | close | lower FPR on target | |
|---|---|---|---|---|
| 2nd | 4.25x FPR | long | 3 cd | burn (100% FPR) |
| 3rd | heal | self | 8 cd | heal + for 3 turns |
Pros:
- Impressive second attack, long range
Cons:
- Weak first attack
- Unimpressive third action with long cd.
Rating: and a half
I think the Gronckle is slightly better, as its first attack (that can be used every turn) is stronger and medium range.