Furnace didn't get the idea of biting on wood. Wood wasn't food. He tried that. But as Kelvin held his arm right. And what felt like surges of negative energy ran trough his arms, he noticed he was gritting his teeth. The wood was a safeguard? This guy was really smart.

When Kelvin gave the signal Furnace concentrated and forced another golden white coil from his hands to dance along his arm.
The sparks sank into the flesh and they both heard the unsettling sound of setting bones. Like wet leather being strained against a hollow tree.

A few sparks missed their mark and jumped up Kelvins fingers instead. Immediately clearing out diminutive cuts amd bruises on his working hands.

"Thmph yuth."
Furnace spit out the stick.
It had deep bitemarks in it.
"Thank you."
He stretched his arms. He felt a little sore, but the pain was banished and he noticed a strong feeling of relief.

He looked around. The structure was unclear in it's function. But appeared well built regardless.
"How can I aid you in return?"