Really? The tadpole gives you power. That brand + gloves = power. Evil coming to bad end is always the case. If evil characters would never follow paths that lead to bad ends there would be no evil in the Forgotten Realms. The Tav who sells her soul to Asmodius is going to end up living in hell for all eternity but she does so to get more power.
. Power you can't use is no power at all.
What the game needs to do is offer a convincing argument that the tadpole is power you can use without it killing you. It could be based on a lie, but the argument needs to be made.