Destroy the lair in the northeast and get the first scarab.
As soon as you’ve built the final hut, you will get a few minutes to reinforce your defense by building more towers. First you will be attacked from all directions over land. Don’t forget to repair your buildings when they get damaged.
The next attack will be from the air. You will now be able to upgrade your towers to arrow towers. You will get a few minutes to do so. The attack will come from all diagonals.
The third and final attack will come both over land and through the air. If you struggled in any of the previous attack, quickly build more towers in your weak areas before the attack starts. Fend off all attacks and you’re done on this island.