The Church is a very important building for mid to late game cities. Each level increases the duration of blessings you use, and unlocks more advanced blessings. For the most part, its effectiveness is trivial until it reaches level 15. The blessings Spoils of War, Good Luck, Emergency Withdrawl and Guardian Angel are the only blessing that are worth actually using. These blessings also only cost gold rather then the gems all other blessings require. You can also heal soldiers which were wounded in combat, meaning you can reuse soldiers which would normally die. 

Spoils of War: - 24,000 gold

Increases the loot gained from attacking camps by 20%.

Good Luck: - 36,000 gold

Increases the chance of finding a rare item when attacking camps by 5%.

Emergency Withdrawl: - 48,000 gold

Your army will instantly return to the city it was sent from when the battle finishes, there is no retreat time.

Guardian Angel: - 60,000 gold

This blessing will revive 20% of casualties you sustain in battle at no cost (separate from the ability to "Heal" your troops after a battle").

For a more detailed explanation of blessing visit each individual blessing's page. Heal Soldiers tab

The church can now heal wounded soldiers, after a battle a certain amount of soldiers will be wounded instead of killed. These soldiers you get to keep but are unable to fight until you have used the 'Cure' button under the heal soldiers tab of the church. The cost is gold and varies based on quantity of soldiers and type of soldiers. Higher level soldiers cost more gold than lower level soldiers.

Until this update came out, using the highest level of military unit was the best, as it reduced losses and thus cost to replace the troops, however with the heal soldiers aspect included into the game, the cost of healing might not be worth it. Therefore one must consider quantity over might or visa versa depending on the players stock of gold and other resources. 

Beaware that there is a cooldown after using the cure button of which you will be unable to cure anymore soliders until the cooldown has expired. Also woulded soldiers will have a 'waiting for cure' cooldown aswell, when this time runs to 0 you will lose these soldiers forever. 

Each city who has a church has the option to cure soldiers, and any soldiers wounded from any attack from any city can be cured in any city. E.g. if you send out 2 attacks from each city, then you can cure all the wounded in 1 city. You can repeat the round of attacks and cure the second round of soldiers in another city...leaving your 1st city's church to finish its cooldown. 

Additionally the 'waiting for cure' cooldown is increased when more soldiers are wounded, so by sending out a continual stream of attacks can prolong the waiting for cure cooldown. However the cure cooldown will also increase, meaning you will be unable to heal more soldiers until it has finished. The best solution is to alternate between cities to make sure you have a cure available at any given time.  Gem costing blessings

1. Craftsman contract - 25x gems

  • Increase your building queue from 2 to 4 for 24 hours ( 33.6 hours at level 40)

2. Peace agreement - 40x gems

  • Protect your current cities from attack by other players for 24 hours (33.6 hours at level 40). Attack another play during this protection time will cancel it immediately.

3. War orders - 35x gems

  • Increase the amount of armies you can send out at the same time from 2 to 4 for 24hours (33.6 hours at level 40)

4.Blessed axe - 25x gems

  • Double your income of wood for 24 hours (33.6 hours at level 40) - Excludes income affected by villages.

5. Mining exploration - 25x gems

  • Double your stone income for 24 hours (33.6 hours at level 40) - Excludes income affected by villages.

6. Alloy smelting - 30x gems

  • Double your iron income for 24 hours (33.6hours at level 40) - Excludes income affected by villages.

7. Harvest festival - 30x gems

  • Double your food income for 24 hours (33.6 hours at level 40) - Excludes income affected by villages. 

8. Golden touch - 30x gems

  • Doubles your gold income for 24 hours (33.6 hours at level 40) 

Max level: 40

Blessing duration bonus per level: 1%

Max blessing duration bonus: 40%