Attacking

Things you should consider when attacking.

Know your objectives
The way you attempt to loot from an island will depend on your needs. You don't necessarily have to win a battle if you just need resources or want to unlock buildings/terrains.

Preparing your attack to the castle
In the following conditions, you should consider weakening the castle by cutting off the terrains around. Your units may die before breaking the castle.
 * When the castle is far from the outer tiles.
 * When the castle's hp is high (i.e. more than 10K).

The need for direct attack on the castle
Direct attack on a well protected castle can end in a failure. Don't forget that the castle can even be broken just by dropping terrains.

Removing traps
Well placed traps can kill many units in one instant. When there are traps nearby the route, you should consider sending Lock Hacker troops to remove them before attacking.

Digging
You can only trace routes starting from the outer tiles. But in case of need you can make a hole of 3 tiles large in order to extend the candidates of the outer tiles.

For instance:
 * Outer tiles before.
 * Digging a hole of 3 tiles large.
 * Outer tiles after.

Note that you can start your route from a tile that was previously an inner tile.

Extended healing

 * Healing spells can be used efficiently by tracing another route over units previously sent.
 * Same for units that are attacking the castle, except that you can use the same route. Once a route reaches the castle, the end of that route after has no sense for units because the game will end once the castle is destroyed. You can use the extension of that last route to heal units, by surrounding the castle multiple times. This will efficiently heal units.

This technique is used in the following video.