This cannon fires purple blasts of energy, and was made with a mixing of the ion cannon tech acquired from Heka , and current Staff Cannon tech. While testing the effectiveness of the ion cannon, Selvans' scientists discovered that, while it did not penetrate the new Goa'uld shields, that it would cause fluctuations in the shields. If a staff cannon shot the shield at the same time as the ion impacted, some of the energy from the staff cannon would transfer through the shield and damage the hull. Thus, with the addition of ion tech into a Goa'uld cannon, a normal staff cannon will still do the same amount of damage, but about 20-25% will be transfered to the hull rather than the shield.