Demonic Statue of the Outer Path

The is a personal summon of Nagato and Tobi.

Background
During the Third Shinobi World War, Hanzō betrayed Akatsuki, fearing they'd grow too strong, having allied himself with Danzō Shimura and his Root ANBU. The ambush resulted in Yahiko's death. Distraught, Nagato summoned the Demonic Statue, which proceeded to pierce his back with a number of black rods, emaciating him. Nagato used the statue to launch a powerful attack, which resulted in the death of all but Hanzō.

Appearance
The statue is a giant, humanoid entity. When first summoned it burst out from the ground, with only its upper torso and arms visible. Its back has a number of spike-like protrusions. When it is first summoned by Nagato, the Statue is blindfolded. During subsequent Akatsuki appearances, nine slots for its (normally closed) eyes are present in the blindfold. In these appearances its arms are also bound in shackles and it has a bit in its mouth. When it was fully seen after being summoned by Tobi, it is seemingly wearing some form of robe, and when seen in Tobi's hideout, its ankles also appeared to be bound in shackles. The long protrusion of chakra amplifying metal from when it connected to Nagato is also present coming from its midsection resembling an umbilical cord. When summoned into battle the statue is not bound by restraints.

Abilities
The Statue is able to emit dragon-like forms of energy from its mouth. When these dragons come into contact with ordinary humans, the humans' souls are ripped from their bodies, killing them. When these dragons surround a jinchūriki or a tailed beast, the tailed beast's chakra is gathered to the Statue's mouth and stored inside for future use. Nagato wanted to use these beasts to create a weapon that could destroy a country. Tobi however, wants to reassemble them into the Ten-Tails. In combination with the Outer Path, the stored tailed beast chakra can be directed and stored back into the previous jinchūriki, and can be quickly withdrawn back into the statue should Tobi desire.

As evident from his enormous size, the Statue possesses great strength, enough to clash with the likes of Chōza and Chōji Akimichi in their colossal forms. It was also shown to be durable enough to take one of Chōji's Butterfly Bullet Bombing punches without even being pushed back, and stop Kitsuchi's Earth Release: Sandwich Technique, just by outstretching its arms. It's capable of creating shock waves that can devastate an entire battlefield, and from the protrusions on its back, launch energy blasts.

Kazekage Rescue Arc
Years later, Nagato made it the means behind Akatsuki's tailed beast extraction. When Sasori and Deidara arrive in an Akatsuki hideout with Gaara, Nagato summons it to extract the One-Tailed Shukaku over a period of three days, sealing it into the statue. When the sealing begins, the bit falls from the Statue's mouth and nine dragon-like entities burst forth from the statue's mouth. As the sealing nears completion, one of the eyes corresponding to the beast that is being sealed opens. After the sealing finishes, the statue disappears.

Hidan and Kakuzu Arc
The statue is summoned to seal two tailed beasts, the Two-Tails and the Three-Tails, during which process Nagato explains Akatsuki's goals. As a result, Yugito Nii dies.

Itachi Pursuit Arc
After Kisame captures Rōshi, the Four-Tails jinchūriki, he and Itachi discuss the sealing of the tailed-beasts. Itachi says that they don't need to rush to capture the Nine-Tails, since that beast is supposed to be the last one sealed, or else the statue would break apart.

Tsuchigumo Kinjutsu Arc
After the Six Paths of Pain capture Utakata, the Six-Tails is extracted and sealed into the statue, resulting in his death.

Invasion of Pain Arc
After Sasuke Uchiha captured "Killer B", the Eight-Tails jinchūriki, Akatsuki tried to seal the beast in the statue, only to see that it's actually a fake.

Five Kage Summit Arc
After Nagato's death, Tobi indicates that Nagato was just a pawn that the Demonic Statue had been synchronised with. He states he would like Sasuke Uchiha to be Nagato's replacement, but decided to wait until Sasuke was easier to manipulate.

Shinobi World War Arc
After accepting the terms of Kabuto Yakushi's alliance, Tobi reveals the statue located within the depths of their headquarters, seated atop of a giant lotus flower, whose stem harbours a copy of Hashirama Senju. Directing Kabuto's vision downwards to the flower's roots, housed in a deeper underground cave, Tobi presents the army of enhanced White Zetsu that he had created using the chakra of the tailed beasts imprisoned within the statue.

During the Fourth Shinobi World War, the statue is summoned to the battlefield in order to assist Tobi in obtaining a substitute for the Nine-Tails' chakra, where it begins to rampage amongst the First Division at Tobi's behest. Confronted then by Chōza and Chōji Akimichi's gigantic forms, the statue withstood their combined assault and with the shock-wave following a bellowing roar, sent the two of them reeling. In the wake of its destruction and in retaliation to Kitsuchi's Earth Release: Sandwich Technique, it releases another powerful blast of chakra, devastating the battlefield further. The statue later attempted to crush Darui and Shikamaru Nara underfoot, when they tried to prevent Tobi from taking the Benihisago and Kohaku no Jōhei.

Retreating to a forested area, Tobi stands atop of the statue's palms alongside his Six Paths of Pain, as dawn breaks on the second day. After Son Gokū is freed from Tobi's control during his confrontation with Naruto Uzumaki and Killer B, he immediately summons the statue to his present location, where it proceeds to draw the bound beast into its awaiting maw and reseals the Four-Tails inside itself. As Tobi continues to observe the ensuing battle from atop the statue, he is ultimately forced to reseal the remaining tailed beasts in the same manner as Son, when they too are freed by Naruto. The statue remained on the battlefield aiding Tobi in his fight against Naruto, B, Kakashi and Guy.

As a combined assault from Naruto, B, Kakashi and Guy knocks the Statue down, goading from Naruto forces Tobi to summon the Kohaku no Jōhei and the Benihisago, which Tobi allows the statue to devour. With a portion of every tailed beast's power now inside it, the statue roars, opening all of its eyes.

Influences

 * As with many of Nagato's techniques, it is influenced by Buddhist terminology., derived from the Sanskrit Tīrthika, refers to any doctrine which "treads the outer path" to enlightenment. This is opposed to the teachings of orthodox Buddhism (the "inner path"), and is thus considered misguided and heretical, which led to a translation of this statue being the Demonic Statue of Heretical Doctrine.