found him in the cellar of the doctor, imprisond and silenced

If you put him out of his misery, you can talk to his spirit and hear his story. He was a famous poet/bard because he made a deal with a voice in the darkness that was the demon inside the Doctor. He was asked to sing about the danger of the Void and the Black Ring, but one day was asked to sing a song of Divinity. You can pass two speech checks to hear it, and then he can go with peace to the Hall of Echoes.

Also found at the Black Bull tavern in Driftwood, reading his poetry in the main hall. You can speak to him and answer some questions, and he'll make a poem based on your answers.

I played as my own lizard character last playthrough and requested an original poem from Tungs here, he sung about slaves toiling and sweating. Later on, in Arx, I asked Creg Ganim to recite a classic and he sung the same song. Albeit much more poorly. Barstan the fraud?