Brunhilde is a shieldmaden and a valkyrie, where she appears as a main character in the Volsunga saga and some Eddic poems treating the same events.
Gambit: Prisoner of War: After attacking the enemy you replenish your troops by making them prisoners of war..
The total potential heal of this effect is equal to her damage, but it is split between the members of your party that are still standing. Also, everyone will receive this portion, whether or not they need it, resulting in most of the healing being wasted.
In the end unfortunately, you will usually get higher total healing per damage from characters like Vlad and Marc Antony.