Hmm interesting observation, it is common, however they can be combined really well if done correctly
so with those combos, we will start with fire + wind.
Now when looking at it, this is probably the most simple of all the combos. When fire is released by releasing a certain amount of wind towards the fire, two things occur.
1. The fire picks up speed due to the wind pushing it forward
2. The fire increases in size and power, because it consumes the wind, feeding from it.
The same is vice versa, so even if you used a wind technique first, then used a fire technique the same effects of those two will occur. That is overall the most basic of reactions between the two, the fire consumes it and feeds on it, increasing size. Think of it like this, get a skinny kid and feed him nothing but junk food, he will get huge and bloated over time. Now that is a small and more real life orientated comparison, but you see where I'm getting at. Wind is the food, fire is the kid.
Now the question also comes up...what happens with the fire? Nothing. All that happens is the fire maintains its basic elemental weakness and strengths, as well as power and defensive abilities. It is just a bigger, more stronger fire. Hence why I dislike this combo, wayyy to singular and not much to really go on, ya feel me kid? Also, realize this small fact, the fire will most of the time act to retain the shape of the wind, if it is sent at it. When done vice versa, the fire simply increases. This includes techniques that retain certain shapes and characteristics. Most of the time. So since I explained it, here is the scenarios I will present to you and you will tell me what will happen.
Ninja 1- Spews a fireball at the opponent (B-Rank), then releases a gust of wind (B-Rank) right behind the fireball which makes contact with it.
What happens to the fireball when it comes to size?
What rank does the fireball retain after wind comes into contact with it?
What Elements is the fireball now strong and weak against? (Just basic 5)
Does it move in the same trajectory and does it move further?
Ninja 2- Here, the ninja releases a tornado made of pure wind that moved along the ground. Then he spews a stream of fire towards the tornado which makes contact with it. Both are A-Rank.
What rank does the tornado retain now?
What happens to the tornado's shape and size?
What elements is the tornado weak and strong against? (Just basic 5)
Does the tornado move the same way as it did before?
Hints- Look back at my writing to help with the answers. Don't feel scared to ask questions. These are basic questions so feel free to improvise if you feel something is off, or tell me through a post and I will make it clear. I just want to know the basics

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