By Joe Osborne From games.com

Empires & Allies, Zynga's flagship strategy Facebook game, just got exponentially more purple. Defense Towers have been released to the game, which allow players to defend specific buildings within a small radius from invasion. More importantly, however, players can attack their friends while Defense Towers are active, though they require a special resource to remain active, Zipp Energy Drinks.

Defense Towers are introduced through a series of Goals, but players are simply given their first Defense Tower through a pop-up that appears. Here's everything you need to know about the Defense Tower and its Goals:

The Best Defense

• Place the Defense Tower
• Complete the Defense Tower

Place the Tower near buildings you'd like to be protected when the pop-up appears. After whacking the foundation three times, another pop-up will appear, displaying the following items you'll need to amass in order to finish the structure:

• 4 Cement
• 4 Nails
• 4 Table Saw
• 4 Nail Gun

Of course, all of these items must be sourced through your loyal, helpful friends. The impatient will be happy to hear that they can buy their way out of these requirements, too. Once it's complete, you will also need to staff it with a few friends. Your reward for completing this Goal is 500 Coins and a Zipp Energy Drink, which will come in handy later.

Fire It Up

• Activate the Defense Tower

This incredibly simple Goal asks you to just click on the Defense Tower and choose "Activate." However, the building can only be activated if you feed it with Energy Drinks and must be continually fed them if you want it to remain active. This Goal rewards players with a measly 100 Coins.

Free Reign

• With Defense Tower Active, Invade a Neighboring Empire
• Collect 1 Black Heart

This Goal is simply to show you that it is, in fact, possible to attack your friends while defending your vital buildings. This Goal's reward ups the ante quite a bit with double the previous reward 200 Coins.

So Sleepy

• Collect 1 Zipp Energy Drink

The final Goal in this painfully simple series tasks you with asking your friends for another Zipp Energy Drink, which is more than likely done through either the Goal menu or one within the Defense Tower.

Notes: Completing this Goal nets you a whopping 500 Coins.

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