Naruto revolves around the use of Nature Types. These types split all ninjutsu techniques into specific categories that allow Shinobi to better understand them. Shinobi can also have an affinity towards certain Nature Types, meaning that they are naturally better at using that type than others. Through immense training and a lot of experience, certain Shinobi are then also able to combine Nature Types and create rare and powerful Jutsus.
Note: This article is subjective and solely reflects the author's opinion. It also contains massive spoilers for the Naruto series.
Ranking Nature Transformations in Naruto from least to most difficult to use
10) Scorch Release
Scorch Release is both a kekkei genkai and a nature transformation. It is created by combining both Fire and Wind Release. The first instance of Scorch Release being used in Naruto Shippuden was when Pakura, a Sunagakure kunoichi, used it in a fight against various Shinobi. She was able to evaporate all of the water from her victims' bodies, leaving their corpses charred and desiccated.
Since it requires the combination of two basic nature types, Scorch Release is definitely harder to use than the five main nature types.
9) Lava Release
Lava Release is another nature transformation kekkei genkai, and seems to appear differently depending on who is using it. For example, it can appear as molten rock (like in the image above), acid, volcanic ash, and other materials. It is formed by users manipulating their chakra to combine both Fire and Earth Release. Some of the most notable users of Lava Release are Naruto Uzumaki, Mei Terumi, Roshi, and Ohnoki.
Despite Lava Release not seeming difficult to use since there being so many characters who use it, the common factor between all the users is that they are all highly skilled Shinobi. They are each one-man armies in their own right and can master complex Jutsus quickly.
8) Boil Release
Like Lava Release, Boil Release is a nature transformation kekkei genkai that appears differently depending on who uses it. It is created through the combination of the Fire and Water Release chakra natures. The most notable Boil Release technique is Boil Release: Unrivaled Strength. This jutsu comes from Kokuo and allows its jinchuriki to gain unmatched physical strength. Boil Release has almost unlimited potential and can be used to create incredibly powerful ninjutsu techniques.
7) Ice Release
Ice Release was first used early in the original Naruto series and Haku is this nature transformation's most notable user. However, the technique is not specific to him. Ice Release is a kekkei genkai of the Yuki clan. It is a combination of Wind Release and Water Release, and results in almost indestructible shards of ice. Moreover, Ice Release has an abundance of techniques that can be used for offense, defense, evasion, and other aspects of combat.
6) Crystal Release
Crystal Release was used by only one character in the Naruto series, a kunoichi named Guren. With Crystal Release, Guren was able to convert any physical matter into red, blue, or green crystals. Although the combination of Nature Types for Crystal Release is unknown, it is presumed to consist of Earth Release in some fashion. Many characters who fought Guren and survived had a hard time defeating her due to the various uses of Crystal Release.
5) Magnet Release
Magnet Release was used many times throughout the series. Magnet Release is the combination of Wind and Earth Release. Both the Gold Dust from the Fourth Kagekage and the Iron Sand from the Third Kazekage are perfect examples of Magnet Release. Naruto used Magnet Release as well when he channeled Shukaku's power and created the Sage Art: Magnet Release Rasengan.
4) Dust Release
Unlike the other entries on this list, Dust Release is a kekkei tota since it is a combination of Fire, Wind, and Earth Release. It is also perhaps the most dangerous Nature Type in the series due to its ability to erase practically anything. Dust Release is an incredibly difficult Jutsu to master and only skilled Shinobi such as Lord Mu and Ohnoki were capable of using Dust Release to its fullest potential.
3) Wood Release
Wood Release is the signature nature transformation of Hashirama and is a combination of Earth Release and Water Release. With Wood Release, Hashirama was capable of creating wood clones, restraining the Ten-Tails, and completely nullifying Kurama's Tailed Beast Bomb. Although the power of a technique is typically based on the user's skill level, Wood Release is inherently strong and will allow anyone become strong. At the same time, it is difficult to master and Hashirama seems to be the only one to have done so successfully.
2) Blaze Release
Blaze Release is thought to be a more advanced version of Fire Release and it is incredibly difficult to use. The black flames can essentially burn through anything and can only be controlled with Sasuke's ability, Kagutsuchi. Amaterasu, a Jutsu considered to be the pinnacle of Fire Release, is the originator of the black flames and is one of Sasuke's Sharingan abilities.
1) Yin-Yang Release
Yin-Yang Release is definitely the hardest Nature Type to use in Naruto. It combines both natures that are exact opposites and exist outside of the basic nature types, Yin and Yang Release. Hagoromo used this Nature Transformation when performing the Creation of All Things Technique and created something out of nothing. This Nature Transformation may be the hardest to use, but it is definitely the most rewarding if mastered.