You can find a full guide [here]. This link will take you to the forum post: "Introducing Grail Wars".

1) How many Marches can a player have in Grail Wars?
Marches from a player's Outpost on the battlefield are determined by Outpost skill levels.

2) How do I upgrade my Alliance Buffs?
Alliance Buffs are upgraded using Alliance Merits. Only specific officers within an Alliance can use Alliance Merits and thus upgrade Alliance Skills.

3) How do I obtain Individual Merits?
Individual Merits are obtained in 1 of 4 ways:

• By scoring points in Grail Wars
• By donating resources to your Alliance
  
• By endowing Crosses to your Alliance
  
• Obtained as a bonus for purchasing Gem packages
  

4) What are Individual Merits used for?
Individual Merit points are used to purchase items within the Alliance Shop.

5) How do I obtain Alliance Merits?
Alliance Merits are obtained in 1 of 4 ways:

• By scoring points in Grail Wars
• By donating resources to your Alliance
• By endowing Crosses to your Alliance
• Obtained as a bonus for purchasing Gem packages

6) What are Alliance Merits used for?
Alliance Merits can only be used by specific officers within an Alliance. They are used to upgrade Alliance Buffs.

7) Do Alliance Buffs work outside of Grail Wars?
Some buffs affect your home world and work outside of Grail Wars. Others can only have an effect in Grail Wars.

8) How many troops can be deployed?
The number of troops that can be deployed depends on the number and level of your Rally Points.

9) How long after an Alliance war ends does the leaderboard refresh?
Almost immediately.

10) Can I be attacked on my home server while participating in Grail Wars?
No, participating in Grail Wars will automatically cause your cities to be protected while you wage war. After completion of the Grail War, the protection of your cities will be turned off.

11) What are the requirements to be able to donate to an Alliance?
The requirements include:

• Embassy level 2
• Player level 3
  
• Alliance level 1
  

12) What happens to my troops?
Of all the troops that you lose in battle, 70% of them will be returned to your Hospital. If you don't have a Hospital built, you won't get them back.

13) What is the Power score based on?
Player Power score is based on the troops, Heroes, Knights and gear they bring to battle. Alliance Power score is the sum of its members' Power scores.

14) How is the Glory score calculated?
Glory changes based on the whether an Alliance wins or loses the battle, as well as the difference between the two Alliances' past Glory record.

15) Will troops killed during Grail Wars count towards troop kill leaderboards outside of Grail Wars?
No, they will not.