Final answer:
Nullification Field, an ability for The Xxcha Kingdom in Twilight Imperium, requires Warfare 2 technology.
Step-by-step explanation:
The requirement for the Nullification Field ability, which is affiliated with The Xxcha Kingdom in the board game Twilight Imperium, is B. Warfare 2. This means that, to obtain the Nullification Field ability, a player controlling The Xxcha Kingdom must first research and develop the Warfare 2 technology. In Twilight Imperium, technology advancements such as Warfare 2 come with prerequisites which players need to fulfill before they can acquire more advanced technologies and abilities like the Nullification Field.