Cage Fighter

Adapted by a Kenku artificer who was too afraid to try it for herself. Instead she replaced the head piece with an enchanted cage containing a pair of your more cunning ravens. Between them they control the stolen duergar hammerer, a digging machine and siege engine, normally used to dig tunnels and besiege enemy fortifications. 

Unfortunately for the artificer, when the ravens' demands to be released were ignored, they put the nee-hammerer, now cage-fighter, through its paces. On the Kenku. 

The tests were successful. 

(The two emaciated ravens, sustained by the suits psychic magic, continue to seek freedom. And also continue to fly into rages when people fail to succeed in releasing them.) 

Duergar Constructs (for context)

Creative duergar engineers have built numerous war machines, including some that can be fused with a duergar. Such a duergar-machine hybrid is fuelled by the duergar’s psionic energy, and the duergar inside the machine can psychically channel pain into power when attacked.

These machines are deployed to assist with construction projects and war. Some duergar bravely volunteer to become hybrids, while other duergar are forced into the fusion by Underdark tyrants.

NB: This bit is no longer accurate.... Unless incapacitated, the duergar inside a machine can extricate themself from it over the course of a short rest, completing the process at the rest’s end.