Already in EA, if you use the tadpole enough times you become a mind-controllable True Soul (The Absolute tries to control you on the bridge, nearly succeeds, and Shadowheart comes along with her d20-shaped Deus Ex Githyan-kina to save the day.)
That cutscene triggers when you reach an exit from the map and happens regardless of your choices - not only regardless of you using the tadpole, but even meeting Shadowheart and the weapon.
