6. Metal bending- a technique that was remained hidden for many years. It can be useful in many ways but is not a top 5. We see that metal benders can’t control platinum or pure metals. The police force of republic city has the retractable chains which are a very interesting and amazing invention. Metal bending is useful but unless you have any metal on you it’s a useless tool. (Unless you’re on a warship or tank)
7. Spirit- I would like to see more energy bending in book 3. It seems to have a lot of potential to be a great tool. Turning spirits from bad to good and good to bad is very powerful. It must be a hard technique to accomplish since only the Avatar and Unalaq a very spiritual water bender. We have only seen this used a few times but in the future I’m guessing we will see this all the time.
8. Plant bending- Plant bending has so much potential. Water benders can control life, but they’re not utilizing its full potential. We see Yu’s plant bending of a seaweed monster, which was very strong and powerful. The fire nation was still able to bring it down. Plants are soft and spineless; most are easily crushed and would not make a good armor. If I was able to plant bend I would probably have long rope like whips. Maybe have 4 extra plant arms.
9. Lava- A very hard technique to master, that only a fully realized Avatar and accomplish. Being able to bend earth and fire would be useful. A volcano is one of nature’s most powerful tool. The first known user of this technique was the who preceded , who used it to make four volcanoes erupt simultaneously. We also see Roku bend lava at the fire sieges temple. This technique would earn either a 1 or 2 spot if we could see more. Bending 4 volcanos at once seems incredibly powerful but unfortunately we only see a flashback of it.
10.Plasma (blue fire)- We have only seen two people harness this power before. It can only be wielded by fire bender prodigies. I don’t think it has too much difference from normal fire, maybe it’s hotter or something. It’s only true purpose is to show the power of the fire bender.
Honnorable Mentions: Energy- Aang and Korra are the only two known energy benders in history. Aang learned it from the lion turtle and taught it to Korra. Personally I don’t find it very helpful. I know it restored a lot of benders and took some bending away, but now that Amon is dead the only person that would be able to take bending away would be Korra. She will be able to decide who keeps their bending and who doesn’t.