Ultimate Summoning Beast

The was a mixture of different summoning animals that inhabited the animal summoning facility. It was created to be a perfect counter against other shinobi.

Background
The researchers of the facility created the creature to be the ultimate summoning. When Honoka tried to seal it, the creature started devouring the researchers and killed Honoka. The creature afterwards started absorbing the other summoning animals on the island and went into a chrysalis state.

Appearance
In its initial form, it resembled a regular pupa with a large body mass and tentacles and small arms. After emerging from its chrysalis, it grew feet as its body gained a more humanoid shape. It also had a mouth on its stomach through which it fed and had tentacles in the area where a mouth would usually be. It was also shown to be able to partially morph its own body into that of the animals it absorbed such as growing wings to fly.

Abilities
Having been created as a counter towards shinobi, the Ultimate Summoning Beast displays a variety of abilities. It can consume other summons in order to gain their abilities, and it's capable of using genjutsu, which it channels towards its eyes, and ninjutsu, as demonstrated with a Lightning Release attack. The creature could also flap sharp wind that was able to cut Guy's cheek. As the "perfect counter against shinobi" it had the ability to absorb chakra, as witnessed when Yamato tried to restrain him using his Wood Release.

Paradise Life on a Boat
When Might Guy is taken by bird summon, the crew sails to the island he was taken to. Aoba Yamashiro finds the ghost of Honoka there and shows him the ruined facility. Aoba finds the Ultimate Animal Summoning sleeping and reads its mind to learn more of its origins. When Guy, Yamato and Naruto find Aoba, the creature awakens and absorbs the animal summons that followed the others. The creature emerges, now out of its cocoon and attacks the Konoha shinobi with the abilities it has acquired as well as Lightning Release ninjutsu and genjutsu. Guy uses the fifth of his Eight Gates to stall the creature while Naruto prepares for Sage Mode. Guy kicks the creature into the volcano outside the lab; the creature attempts to escape but the bird that captured Guy, along with the other animal summons, prevent it from doing so. Honoka's ghost helps restrain the creature while Naruto tosses Rasenshuriken at the creature, slicing it in half and sending it plummeting into the lava.

Trivia

 * A chimera is a mythological creature composed of the parts of multiple animals, and is also a genetic term for hybrid animals with more than one DNA pattern.