At the moment I am currently working on ranking up my own Drakon so I can't give a perfect review of the ultimates (though I can still give my opinion based of what I have seen in game and from discussions about it with other players)
The Drakon is supposed to be an offense oriented sprite... but in my opinion it fails at that for a variety of reasons. In fact it doesn't seem like there is much use for it until you finally do get access to the ultimates, till then you're going to be running around with argueably the worst sprite in the game.
The Firebolt is a Ranged attack with a small fiery explosion that can flinch enemies (nice) and can set them on fire (meh)
The Flame Barrier is in my opinion a waste of time... the orbs don't deal direct damage or break blocks like the Barrier pickups you can collect... all the Drakon's Flame barrier does is raise your defense and set things on fire, and I mentioned in the Seraphynx review why Defense Up isn't that useful in this game
The Firestorm is an equal waste of time.... the sprite lays down a small patch of burning ground that lights enemies on fire.... I can do the same thing with a Fiery Vaporizer Mk 2 on a much shorter cooldown and with the ability to actively deal damage with the blast radius
Of the base skills the Firebolt is the most useful and even then it doesn't always light things on fire.... to buff this Sprite I'd make the Flame Barrier function identically to the Barrier pickups dealing damage and breaking blocks, I'd also make the Firestorm function like the Drakon Ultimate "Explosive Firestorm" where it actually creates an AOE that not only burns enemies but can also deal damage.
In addition I would (similar to the Maskeraith in my other review) give the Drakon the unique "DragonFire" status... functionally identical to fire but it bypasses immunities and won't light up Oilers/Toxoils
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As for ultimates (from what I've seen and heard)
The FireBolt ultimates are both pretty nice actually... upgrades but not really game breaking.... the only thing I might change is Blast radius on on the Meteoric by a small bit and to increase the Stun chance on the Concussive
The Flame Barrier ultimates are one of the things that make Drakon so good... The Backfire Barrier is a great tool for escaping bad situations or speedrunning in general, extremely valuable in this game.... the Scorching barrier on the other hand is hardly an upgrade but this goes back to the Barrier's inability to deal direct damage like the Barrier pickups... if that gets changed then I could see this ultimate being very useful for melee attackers
The Firestorm ultimates are also very good.... the Explosive Firestorm finally lets your ability deal direct damage (which it should have from the start) making this a potentially powerful too for players.... unfortunately it's entirely overshadowed by the Frenzied Firestorm, why deal damage with your sprite when you can get it to give you a boost to deal damage with your own weapons which are far more powerful than the Firestorm? The Frenzied Firestorm is the clearly superior choice right now. If the Explosive Firestorm is granted a much higher damage output, maybe explosions that have an extremely high flinch rate and 0 knockback it could prove to be a valuable option for locking enemies in place while dealing damage to allow for a brief respite from attacks or for the knight to join in...
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The Concussive Firebolt, Backfire Barrier, and Frenzied Firestorm are some of the best ultimates in the game... the problem is that until you get to MAX level your sprite is far less useful than the Maskeraith with it's poison and Cloak utility, or the Seraphynx and it's HP drop booster and Shield....
Fire is a good Status but for the Drakon the slow death by burning enemies means that the amount of DPS you actually add to a team is minimal and would be better used on something like support.... Right now the Drakon is too "passive" in how it deals damage and this game is more rewarding to just kill things...
"The Flame Barrier is in my opinion a waste of time... the orbs don't deal direct damage"
That's untrue, Fire Barrier deals 101 damage per tick, in T3, level 75 (5*).
"The Firestorm is an equal waste of time"
Base Firetorm is absolutely bad, but it shines when you are in a freeze level without any fire weapons, otherwise, yeah it sucks.
There's also worth noting that Drakon deals Moderate fire considering you put all points on increasing the fire strenght.
"...the Scorching barrier on the other hand is hardly an upgrade but this goes back to the Barrier's inability to deal direct damage like the Barrier pickups... if that gets changed then I could see this ultimate being very useful for melee attackers"
Again, untrue, Scorching Barrier has a 50% base-ish increase, meaning that you'll still deal 101 damage in T3, level 95 (5*), but since you have an extra orb, they orbs rotate faster, and they are bigger (meaning you'll get more consistent damage) you'll deal much more damage overall.
" unfortunately it's entirely overshadowed by the Frenzied Firestorm, why deal damage with your sprite when you can get it to give you a boost to deal damage with your own weapons which are far more powerful than the Firestorm?"
Firestorm can flinchlock a lot of enemies, meaning that you can lock a lot of enemies and deal up to 2000+ damage overall with Explosive Firestorm, using the right harness, that's insanely good, of course Frenzied will deal more damage, but Explosive is useful if you want to flinchlock a group of enemies and deal with another one whilst the other group is being flinched to death.