Talk about it here.
Danna Dementara was the finest military strategist in Gallifreyan history. She mentored young Irving Braxiatel at the Academy, teaching him to be a diplomat and a soldier. She also taught him how to shoot down a whole flock of Pazithi bats with one shot.
Before the Last Great Time War, Braxiatel placed her on a research station near the Obscura not only so she could study the Daleks who were trying to understand the Obscura but also so she would be hidden, as Braxiatel thought her abilities made her a dangerous weapon. However, while on the station, she aged and withered to the point that she could "no longer shoot straight."
Danna met Ace when Braxiatel came to visit her. She told Ace that she wanted to see Earth after she left the Obscura. Braxiatel discovered that her abilities had dulled and allowed her to be executed by the Daleks. Danna later haunted Braxiatel as he made his final plan. (AUDIO: Soldier Obscura)