good hint to save your islands.
If someone would like to blockade your heaven and you does not have a lot defense units but have a good offensive then next tactics 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 you force should be out before blockade starts.
3. Don’t worry if enemy blockade your islands. wait for offensive forces 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 blocked). In this case your offensive units should be back between waves.