I'll add in card images soon.
I'm not saying this card is VERY underpowered... I'm just comparing it to gnome rider, damselfly and photon.
Clearly, spark is not a problem.... since it has a very nice damage/cost ratio. However, of the upgraded... ball lightning is the worst -- in 3 turns, damselfly OUTdamages ball lightning AND gives 3 
. Also, although it is really easy to kill... the opponent has to waste CC on the creature. Maybe the problem isn't ball lightning, but rather the other cards... but I would say something is unbalanced here.
BTW, in a cremation deck, use gnome gemfinders... because of the whole lava golem thing....
I have absolutely no idea what you are talking about. How is BL WORSE than Spark? It has a higher damage, and nothing else. Both have the same damage/cost ratio, infinity.
I really hope you're trolling.
Damselfly out damages spark in 2 turns. There is nothing unbalanced, that's how the card is designed, like a quick burst of energy to your opponent.
He's comparing them in the respective unupped & upped environments. "However, of the upgraded...", it could be more clear, but it's still understandable.
Let's compare BL against the "surviving" competitors:
-As Immolation fodder: same value, as all of them do the same when immolated.
-Creature + buff: BL has the highest attack and why would you care about Hp in a rush? (and why would you buff a weak card in any other deck type?).
-Death effect activator: only BL dies.
-In a Fractal Blitz deck: Damsels generate
, which is good, but the whooping 10 damage a BL gets outshines the meager 4 damage of Damsels (and take into account that there might be shields). BLs kill in one turn, so there's no problem with them dying on that one.
-As a quanta generator: BL does not generate quanta; RoL, Damsel and Gnome do. No question here.
-As burst damage: Damsel outdamages BL in three turns. As this is used only for Immolation decks (which win in 5-7 turns), BLs are actually better here because they deal 5 damage no matter whether you get them on the first turn or on the last one.
Conclusion: they all have their place: Immobows, Fire Rushes, Air Rushes, Earth Stalls, RoL/Hope... Each deck type benefits the most from using one of these creatures (actually, with Fire Rush you can swap BLs for Gnomes and change your mark without a big penalty of buff). I we were to illustrate this with an extreme example, nobody would use Dragons as Cremation fodder, as nobody would use a Tower Shield in an Earth Stall.
