Defend Berk is a game mode where you and your dragons must protect your Berk from Alvin's forces. You will put together a team of 4 dragons to fight against Alvin's ship fleet attacking your Berk. To play Defend Berk, tap on Berk's Duties and select "Defend". You will be shown the current fleet and the option to start. Note that you must have your Meade Hall at level 5 to play this mode. An additional dragon slot will unlock at Meade Hall level 11.
 
Once in the Defend Berk menu, you will be able to choose the dragons you want to have on your team. You will also be shown your chance of victory based on your team's power level and have the option to make repairs if you have recently played a match of Defend Berk where you took damage. Note that each battle costs Wood to start it.
 
Once the battle is started, you will be given 30 seconds to scout the battlefield. Tapping on a ship will give you more information about it.
 
Once the battle starts, you can place your dragons in the battlefield by selecting your Dragon on the right side of the screen and then tapping where you want to place them in the battlefield. They will automatically attack the closest ship. Destroying smaller ships (purple health bar) will inflict damage on Alvin's main ship (red health bar), making it easier to destroy. They will not go down without a fight, however, and will attack your dragons when they get close.
 
Alvin's ship will damage your Berk's health over time. Less health means less rewards (and eventually defeat), so be sure to be swift! Fortunately, you also have some tools at your disposal:
  • Catapult: Throws a fireball wherever you tap on the battlefield.
  • Flare: Directs your dragons to move to wherever you tap on the battlefield.

Keep in mind, however, that using these costs Energy. You collect Energy by destroying smaller ships. The more you use a particular tool, the more expensive it will become.

When you win a battle, you will receive Battle Keys to open any of the 4 chests you will see at the end of the battle. These will contain random rewards: Fish, Wood, Iron, Runes, and Gears. Gears are used for Collections.

If you feel like you will not win the battle or simply wish to cancel, you can retreat by tapping the button on the upper left hand of the screen.