I think, overall, that most of the good points have already been made. However, I'd like to go over (and rehash in a couple cases) some of the dilemmas in the /fire secondary set. I can only speak for this set, as it's my only blaster AT at the moment.
Ring of Fire:
This isn't really a problem power, per se, except that many enemies can avoid the immobilize aspect of the power. Try using it on any large enemy (as in most bosses, any large minions like Abominations and Embalmed Aboninations, etc) and you notice that they may take damage, but they aren't stopped.
Combustion:
Utterly useless. I can do more damage faster when I hit fire sword circle. As others have already said - the damage is DoT which is fatal to a blaster. Couple that with the slow animation and minimal damage and you have a power that really doesn't work.
Blazing Aura:
I have this power on my tank. I love it. But I wouldn't imagine using it on my blaster as it just further angers mobs that are already too close for comfort.
Hot Feet:
I agree with the other posters who have said this power would be of more use if it weren't the level 36 power.
Rain of Fire:
I LOVE this power, except for two things - one is the unbuffable nature of the power (which, I believe, was partially patched recently). Even SO damage enhancements don't seem to affect the damage done by this power. The other issue is the fear aspect - it seems that before any meaningful damage has been done, the MOB has fled the effect area.
Overall:
Blasters are meant to keep enemies at a distance and unleash their damage from there. However, as others have pointed out, most groups have higher range and can close in to melee while a Blaster is rooted trying to fire attacks. What would be useful is some level of immobilization for groups to keep them at a distance. Giving an auxilliary soft-immobilization power to the /fire set would make it much more attractive and useful.
That's my two cents, at least.
On a side note - thanks _Castle_ for taking the time to review these issues.
