10. Undead Invasion

Once a week, an R4 or R5 must initiate the Undead Invasion if the alliance is going to participate.  When this happens, ALL alliance members will be attacked by 20 waves of undead warriors, led by the dreaded Undead General.  They will march upon your city whether you are bubbled or not.

But do not fear!  Worst case scenario, your troops get wounded and you have to heal them.  No troops are killed.  Also, if you don't want to even participate at all, just wait until the invasion has started and use a random port or adv port.  Porting immediately cancels the invasion for you.  Also, you can send all your troops out of your city on long marches.  After your city is hit two times and you fail, you will be out of the event at that point as well.

BE WARNED!!!!  Most alliances don't like it when players don't participate in Undead Invasion.  This is because the better the alliance does as a whole, the more rewards and gems everyone gets from it. 

So if you are unable to participate at the time the Undead Invasion is activated, your defenses will survive wave after wave without you until your Kill Rate drops below 50%.  Basically, Kill Rate is just what percentage of Undead Troops you killed before the wave ended.  In other words, there are a set number of rounds each wave that your defenses must survive.  If you survive all those rounds and have killed all of the Undead Troops besides, you have a Kill Rate of 100%.  If you only killed half of the Undead Troops during that wave, then your Kill Rate is 50%.

Again, fail to get a Kill Rate of 50% or more, and your Defense Failed.  Fail two times and you are out of the fight.  This means that no more waves will attack you. 

However, just because your defenses failed twice and no more waves are attacking you, it doesn't mean you are out of the fight altogether.  You can still Reinforce your alliance members.  If you do, you and your alliance member that you are reinforcing get points for how many Undead are killed.  So when you are knocked out, Reinforce others and keep fighting.

Things to Know and Tips:
1. Undead do not plunder your city's resources.
2. The Undead's Power increases every wave, making it really hard to make it to the 20th march.
3. Remember, Truce Agreements do not stop the Undead Invasion.
4. Sub Cities do not fight for you during Undead.
5. Remember, unless you want to NOT be in the Undead Invasion, don't use any kind of City Port.
6. You will not receive any rewards if you don't at least participate, so it is better to fail the first two marches by sending troops off your city and killing Undead with some traps then it is to port.
7. BUBBLE at all times during the Undead Invasion.  If you do not Bubble, enemy players will see the Undead Invasion march lines and follow it to the hive, looking for players they can kill.  If you are unbubbled, you are a big target because everyone in your alliance is busy trying to work together to fight the Undead.  Besides this, if someone Reinforces you while you are unbubbled, and an enemy attacks your city, your ally just lost a whole lot of troops too, making it even harder to do Undead for them as well.
8. Don't Reinforce anyone who is unbubbled.  Let 'em burn.  It happened to me before.  I was Reinforcing an unbubbled city during Undead and some jerk came in and wiped out my troops and that unbubbled player's troops.  I learned not to make that mistake again.
9. HEAL!  After every wave, heal your troops.  That is really the only way you will make it to the 20th march unless you are REALLY tough.
10. ALLIANCE HELP! Hit the Alliance Help a lot during Undead Invasion, between waves, so that you can help heal your fellow alliance members' troops.
11. USE BUFFS!!!  After the first wave, go into your Items menu, to the Special Items tab and use an Attack and Defense and HP increase, if you have any.  These will only help you survive with less wounded.
12. PUT ON YOUR MONARCH GEAR!  In your Monarch gear, there is a Medicine Crown that helps you heal faster.  Also, putting on gear that gives buffs to Ground and Ranged troops will help them fight better.  You don't need mounted as much as Ground and Ranged at this point, so focus on them.
13. Most alliances find that the best strategy is to send their best, toughest members to the nearest White Mountain where the Undead Invasion will spawn.  The White Mountain it spawns from is determine by who initiates the Invasion.  So if the R5 initiates the invasion, the Undead will start from the nearest White Mountain to the R5.  Choosing a White Mountain that is at least an hour away from the rest of the alliance allows the First Wave of Alliance Members to endure all 20 rounds alone before the first wave of Undead Troops reaches the rest of the alliance.  Once they have endured all 20 rounds, these big members port back to the Alliance City (also known as the hive), and they will then reinforce smaller players to help them get to 20 waves as well.  The more who can do this, the more successful the alliance as a whole will be and the better the rewards.  Some alliances even do two Alliance Waves, setting the first at the White Mountain and a second halfway between the First Wave and the hive.  I'm not sure really how much more effective this really is, but some swear by it.

Finally, and this is just a little extra, upgrade a building or two during Undead.  Every time someone hits Alliance Help (certain restrictions apply), your timer goes down on your building.  You can burn through some serious upgrade time by upgrading during Undead.