Tunstall served as Griffin's head physician during the Pandoran War, staying aboard the carrier throughout all its major missions and conflicts.

Tunstall temporarily removed Parks from duty as captain of Griffin when the ship travelled to the core Mitikas systems, due to fatigue. He was concerned that Parks had overstretched himself and would not be able to fulfil his duty as captain correctly. He confined Parks to his quarters for forty-eight hours.

After years of exposure to the Pandoran soldiers, Tunstall was well versed in how the nanomachines operated. When Simon Dodds discovered a dead Pandoran soldier on the La Machine Infernale 1800, Tunstall gave a demonstration of normal and mutated nanobots, describing how the replication process had gone wrong.