I would suggest from my own experience...to avoid the combustion and fire sword circle and take the two auras...
Lets face it....you are blaster not a melee player....you want to actualy hit and kill things...even hit and kill those paragon protectors and superior reflexes enemies.
You dont want to have to interupt your best attack chains to use some melee attack powers that consume alot of energy and use alot of animation time.....time in which you might have killed something already.
Again this is this just a suggestion...
Combustion - This power is just bad. At its best, its meh. Unless you plan on spending a lot of time fighting +4s. So, if you like to AE farm or will play a lot of challenge teams, it can be useful.
Fire Sword Circle - Excellent power, although the added animation time has hurt it significantly. I haven't skipped this on a /Fire blaster in a long time... a long time.
Hot Feet - Excellent power if you plan on spending a fair amount of time in or near melee. This really is a gem once slotted, but you have to be willing to get in the bad guys' faces.
Blazing Aura - With Hot Feet, if you LIVE in melee, this can be a good power. Most blasters will not play that way, so I'd recommend skipping it. It is also quite an end hog, using 50% more endurance than the armored AT version (for no apparent reason, although if it was simply a bug I'd imagine they would have fixed it by now, so there must be some reason).
Consume - Despite its drawback (recharge too long), you don't really have another option, so I recommend it.
Burn - It does the same damage as the Tanker/Scrapper/Brute version. As a fire/fire blaster, you will probably have better options recharged. Its not bad, especially in conjunction with Ring of Fire, but when you can Blaze or Fire Ball or Fire Sword Circle, Burn really loses its luster.
Why Blasters? Empathy Sucks.
So, you want to be Mental?
What the hell? Let's buff defenders.
Tactics are for those who do not have a big enough hammer. Wisdom is knowing how big your hammer is.
The best of /Fire are Ring of Fire, BU, Fire Sword, Fire Sword Circle, and Consume.
Fire Sword Circle is a very good PBAoE attack; however, it does slightly less damage than Fire Breath and you will have more trouble catching enemies in its radius. Fire Sword is a decent ST blap. Consume is very nice for recovering from your nuke's crash (use Inferno, eat a blue, hit the surviving bosses with Consume, continue blasting), but the long recharge means that you can't rely on it to solve endurance problems.
Burn has a 8ft radius, is a DoT, and causes scatter. I found it impractical to use as an attack on my Blaster for those reasons and you cannot use it while in the air (if you took Fly). I have no experience with Combustion.
On my Blaster I have both Hot Feet and Blazing Aura. They add decent damage without eating up valuable animation time in combat. But it's hard to recommend them in general. They are very endurance intensive (Blazing Aura is flat out broken; it does less damage than the Scrapper version for a greater endurance cost), and to make them useful you need to stand around in the middle of large spawns, rather than jousting PBAoEs or jumping out to use Fire Breath. And the advantage they offer is negated if you have to constantly retoggle them. You should probably skip them unless you're really sure what you're doing.
Thanks for the helpful replies. For me, I think I'm going to go with:
Fire Sword Circle - the only option I want to take available at this level, considered Blazing Bolt, but not sure how much I would actually use a snipe.
Consume - as I mentioned
Burn/Hot feet - I look at these as soft control for when I solo. I can immob one for some extra damage, and scatter the rest if I get overwhelmed.
Just a quick note on Combustion. Combustion's strongest selling point: it's an awesome costume change power. It's so good as a costume change power, I still pick it up on every character I can, even after costume change emotes got implemented.
I'm level 26 right now and looking for a little extra direction. So far I've gone mostly primary with all the ranged and am wondering what are the best choices from the secondary. I'm pretty experienced with fire melee (45 fire/fire brute, 30 fire/fire tanker) but I'm not sure what works the best with the blaster mentality - this is my highest blaster. I PuG a lot on this character, but also typically solo. Wonder what the best secondary choices are.
Combustion: Has a wider range, but has slightly lower damage and a slow animation.
Fire Sword Circle: My favorite on my melee characters, but does have a shorter range.
Blazing Aura/Hot Feet: Hot Feet seems like a better choice for a blaster with the slow and fear. Is it useful to have both?
Consume: My favorite power, it could be better, but I love it.
Burn: Also love it, again could be better, but I still love it.