Firestarter

[Orophin]

I personally have not been queuing my Fires since learning Firestarter as I don't want to waste the time cancelling. It doesn't seem beneficial to continue a Fire cast as it has the chance to proc another Firestarter and you missed out on the opportunity to get two back to back.

Also regarding Thunder, I haven't learned Thunder 3 yet, but I've been using Thunder 2 as an opener since the high 30s and on since mobs last a little bit longer now. Getting the chance for the Thunderspark proc seems worth it IMO. I am pretty sad they disallowed the stacking of the three Thunder spells. I used to use these as a filler waiting for my mana to recharge after swapping to Ice.

[Rbstr]

I've noted when Thunder procs I can get it off almost exactly in time with my current FireI cast. Then go into the next FireI cast after the cooldown resets.

Seems to me that even though you have a chance for that FireI to proc it's better to get a half-casted spell off than interrupting it unless you'll pop the mob with it:
Each cast is an individual proc event. You're not "missing out" on a back-to-back except hypothetically. Even then It's less likely that Firestarter will proc again on that FireI than not.

[Enzo729]

As for not spamming Fire 1, it's a give and take, because in the time you wait for the previous Fire 1 to hit to see if you got a FS proc you could of casted another Fire 1. So basically if you're trying to optimize DPS, it would be better IMO to spam Fire 1 and just cancel whenever it procs. Overall canceling 5-10 times a fight is much better than delaying 30+ fire casts.

As for Thunder, I always hard cast (opener and reapplying) Thunder 2 due to shorter cast time and use TC procs on Thunder 3.

[RonPierce]

Yeah generally its like the main spell is whatever element it is or spell name it wants to take, then the AOE version adds aga (or ega depending on the game). I don't quite remember how they handled purely stronger nuke versions of spells. Personally I'd prefer a whole new spell name to separate the varied abilities that are just more potent/costly, because the I II III system confuses new players into thinking they're replacements.