Hammer's Gear

Hammer's Gear is a Gear piloted by the character Hammer in Xenogears.

Description
Hammer's Gear is made out of human parts on the inside. As such it acts more like a cyborg than a Gear. It responds to the wishes of the pilot integrated within it and uses Ether to transform. With strong desires it becomes a much more powerful Gear. The Gear is able to develop a tail and many tentacles as part of its transformation.

Analysis
Hammer greatly desired power so he could be similar to Fei and his other former friends. After betraying the group, Krelian merged him with this Gear, enabling Hammer to finally wield great power. Krelian sent Hammer to the second Anima Dungeon in order to take the Anima Relic there as well as Elly. The party reluctantly fights him during which Hammer's Gear grows more and more powerful. Either through Hammer's Gear self-destructing, or because of being defeated by the party, the Gear is destroyed and Hammer falls to his death.

As a boss

 * Hammer (Anima Dungeon Two)