In Empires & Allies, combat is not restricted to the campaign map. Not only can you take the fight to the Dark Alliance, but you can invade your friends’ island empires. This exciting and dynamic player versus player combat not only awards combat drops and XP, but you gain resources plundered from the occupied nation. Remember, you can invade your friends, and your friends can invade you.
All players can participate in Player versus Player (PVP) combat starting at level 6. When you reach level 6, you can invade your neighbors. To invade a neighbor, click their picture in the ladder. When the menu for that neighbor appears, click Invade. This takes you to your neighbor’s Empire.
When you are in your neighbor’s Empire, you see a green 5x5 square and a red crosshair on the screen. This shows what part of the Empire you will occupy if you win the invasion.
Any buildings in the occupied area provide resources for the invader and cannot be used by the occupied player. The amount and type of resources you will gain from the occupied area are shown next to any buildings under the green square.
After picking where you are going to invade, the combat screen opens. If you are attacking unprotected buildings, you will face a force of randomly generated units based on the defender’s level. If you attack protected buildings, any units protecting those buildings along with additional units will be in the defending force.
Combat in invasions works the same way as during a Campaign except that you do not need allies and cannot use Powerups. Like campaign combat, units killed in invasions give reward drops.
After the battle is won, you return to the occupied Empire’s map to collect the reward for the invasion. This reward includes the resources shown when you first chose your invasion site and one Infamy point for each building plundered. You can harvest this plunder every 24 hours your forces occupy the area.
Your empire can also be invaded by your friends or minions of the Dark Alliance. When this happens a red 5x5 square will appear on your map with the avatar of the invader hovering over it.
As long as the buildings remain occupied they cannot produce anything for you, the only way to regain control is to repel the invader. To repel invasions first you must click on the avatar over the invasion site. You will be given two options:
If you choose to Attack you will enter the combat screen. Once you are in the combat screen you will be instructed to pick units and do battle with the invaders. If you win then they are driven off of the island.
One way to deter invasions is to deploy units near your buildings and protect them. Any units protecting a building will be part of any battle involving the building they guard along with any other randomly picked units. A unit shows what buildings it can protect with a blue field that surrounds it. Any building with the word Protected on it will be defended by that unit during an invasion.
Friends can come to your island and fight against the invasion for you. Asking for help brings up a feed inviting your friends to come to your island and drive out the occupiers. You can also repel invaders from your friends’ empires by visiting them and clicking on the avatar over the occupied buildings.
If you do not want to participate in PVP play, keeping your Empire safe and secure is easy to do. When you reach Level 6, you receive a new quest that prompts you to place a World Embassy.
The Embassy, while active, protects you from invasions by other players and the Dark Alliance. The Embassy protects you as long as you do not invade other Empires.
If you launch an invasion, the immunity ends. The Embassy can be activated for 18 hours; additional blocks of time can be purchased for Empire Points or by hiring friends for each additional day of immunity.
You can check if your friends have immunity or need help repelling an invasion in the Neighbor ladder at the bottom of the screen.
A neighbor who currently has immunity will have the Shield icon:
A neighbor who needs help repelling an invader will have a box with an exclamation point:
Source: Empires & Allies Guides