Rōshi's Jinchūriki Forms

Rōshi was the jinchūriki of Son Gokū — the Four-Tails. Not much is known about Rōshi or his tailed beast except that it had ability to mix its earth and fire natures to create lava, which it spewed from its mouth. Due to being its jinchūriki, he also possessed this ability. Rōshi was eventually captured by Kisame Hoshigaki and the beast extracted, causing his death. However, during the events of the Fourth Shinobi World War, he was reincarnated and made into a jinchūriki once again, yet the Eight-Tails remarked that his tailed beast felt "different".

Version 2
Whilst reincarnated, Rōshi displayed the ability to enter a "Version 2" form, by moulding its chakra into a human-like shape around himself. When entering into this form, the sudden increase in chakra was such that it instantly vaporised Killer B's ink clone, which had immobilised him at the time.

In addition to forming a dark chakra cloak around his entire body, he also gained prominent tufts of fur along his back and the characteristic horns of Son Gokū on his forehead. With the power granted by this form, Rōshi not only manifests all of his beast's four tails, but also becomes able to summon even larger torrents of lava than normal almost instantaneously, which can erupt violently upwards from the ground.

Partial Transformation
After being reincarnated, Rōshi demonstrated the ability to manifest one of the beast's tails. In this form he can envelop himself in an armour made of lava. The extreme heat generated by his armour is strong enough to burn his opponent, even without coming in direct contact with them.

Full Four-Tails Form
While fighting Naruto Uzumaki and Killer B, Tobi forcefully transformed the revived Rōshi into his full Four-Tails form. In this form, he takes on the appearance of Son Gokū itself, allowing him to manipulate the full extent of the beast's considerable physical strength, with which he was able to easily throw B despite him being in his full Eight-Tails form.