We have collected the most common questions with regards to war-champions and war-shields. We will continue to update when new questions arise.
A good general description of war-champions and war-shields can be found in the update notes for version 1.8.5.
Do the costs for champions and shields rise with each Alliance level?
As for elite boosts the costs rise with each Alliance level, because the ability to earn Alliance gold also increases with each Alliance level.
Do the champions and shields only count for future attacks or are they calculated retroactively?
The champion and shield slots count only for future attacks after being activated.
When activated, do the champion and shield slots are active for the full war season?
A player who is appointed to be a champion and a player who gets shielded will receive the status only for a single war.