Good hint to save your island.
If someone would like to blockade your heaven and you do not have a lot of defensive units but have a good amount of offensive units, then the next tactic is helpful:
1. Check time when enemy is attacking your heaven
2. Before attack (few minutes early ) move your attack force out (by attacking small islands near you). Keep in mind that your force should be out before blockade starts.
3. Don’t worry if the enemy blockades your island. Wait for offensive forces to return.
4. Take a look how your offensive forces unblock your heaven by killing enemy attack forces (This is easy task)
Some players like to send two waves: first with offensive tasks (for killing your defense), second one with defense units (for keeping your heaven blockaded). In this case your offensive units should be back between waves.