Excellent. Quiz time for A-ranks, you know what to do.
*cracks knuckles*
Alright here we go
For the first technique, the flame flower jutsu is an excellent jutsu for distraction I would say. You're using the flame balls to create a large gyser of flame. This would be good if you're trying to burn things or the terrain. It's rather wide thanks to the three flame balls themselves, however if you think about it this jutsu has a huge flaw. That would be the fact that the jutsu could be side stepped rather easily if you think about it. Also in the time it takes for the balls to actually reach the ground your opponent could use a water jutsu of some sort to douse the flames before they reach them.
With this next jutsu you're basically making dinner here. With the assistance of the two jutsu needed to perform this technique, if you succesfully trap your opponent in here, there is virtually no escape and once you set the fire in there, you're instantly chared to bits. However the biggest problem with this jutsu is the fact that you need the earth and lightning techniques in order for it to work. You'll need to set up the oven and that in itselfe poses the problem, if you don't capture your opponent within the walls using this jutsu would be useless. This is best used on large targets like summons, however you have the problem of setting up the oven and making sure your opponent is inside the oven before you actually use this jutsu.
The Great Dragon fire technique, could be used in the same way as it's parent jutsu, to be used to alter the weather in order to prepare for Kirin (if that's in your arsonal) or to simply alter the weather. Also a useful trait, the grand scale of this technique, if you launched this at your opponent, could be used as a great distraction, or to cause damage to the area, lay waste to teh terrain or if you have them trapped, simply finish them off HARD xd. However these balls are rather large and takes some time to exhale several of them (four I think is the max) and a rather strong water jutsu (B could cancel it out, A ranked water could end it quick) would be enough to render the entire jutsu uselss and the individual balls aren't that hard to defeat by themselves.
Same as it's parent jutsu, you're creating an ash cloud to cover over your opponent and to capture them in a flaming explosion. The use of this technique is rather straight forwards in terms of it's best use. Capture your opponent in a smoldering black fog. The fog itself burns and clouds your vision and makes it hard for you to breath. Click your teeth and it's all over for them if they're inside. Trapping your opponent inside here gives you the advantage of blinding them and hindering them from escaping or making it harder since the breathing issue. However since this is smoke, regardless of the rank if you had a large enough gust of wind to blow this smoke away, it's useless and also if you manage to get out of range of the cloud that also helps in defeating it.
Intelligent Hard Work is my favorite Katon technique. You can either make a compressed ball of fire and shoot it out and make it explode into a large flame or you could make it into a large storm of flames on the ground and send it to overwhelm your opponent. Once you send it out, you're opponent is like DAMN lol. However there is the problem of it blocking your sight of your opponent in a way. I mean that could allow them to do all sorts of things. They could go underground if they have earth and set up a clone to make it look as if they were hit. The loss of sight of your opponent is always a disadvantage.
The crater jutsu, I find this technique best used if you're a sensor and you're opponent is aware of your position. If you do this fast enough and trap them, they're sitting ducks. However this jutsu is only really good in such a situation, either that or if your opponent is trapped. The reason is, because you're in the time it takes for you to stomp on the ground breath fire into the tunnle, make the seal and have it erupt, that's enough time for you're opponent to say "hell no am I waiting for this" and move out of the way. You would need to confirm your opponent wasn't/can't move where you initially set up the tunnle first and then make sure he stays there so he doesn't evade the jutsu.
Finally the jutsu I just learned. When combine with the jutsu I just did, Great breakthrough, you have a great Wind Fire combination to expand the flames and it's range, however simply put, the jutsu by itself isn't that impressive without the wind to back it up.