From what we have at the moment in the EA's story, which theme are you talking about ?
What you're willing to sacrifice for power/how much are you willing to surrender to a corrupting influence for power. Everytime you use the tadpole you surrender a bit more of yourself for re-rolls or successes, ect, you start getting dreams essentially telling you to continue using the powers, to surrender and become even stronger. Baldur's Gate I and II was about embracing your divine heritage or resisting it, though due to writing, tech, or time, it was more informed (good characters could heal minor wounds, evil ones could vampric touch for example). It was never really said, but the start of ToB (the first challenge room) the npc mentions they embraced and became consumed by the essence
