This dank swamp contains many abominations that are threats to any kind of civilization. This is likely the first real challenge that the Master encounters; all Acts before this are not this tough. The Master will have to travel through a deep swamp and navigate through temple ruins before reaching the end, all of which are guarded by native animals and protective guardians.
Right away, the Master should cause an Earthquake in order to link the main and northwest islands together. Also, zapping the east section of woods on the northern eagle-like island with Lightning will burn down a tree that the people will investigate once they've been given the Ancient Tablet from Kasandora (they'll find the Magical Aura spell). Other than that, the Master will have to use nearly all Miracles in order to tame the islands and provide room for civilization's growth. This is relatively small area, though, and won't require as much work as previous areas.
Once again, sowing Wheat right away is important. The monsters are thick here, and the Angel will have his hands busy fending them off. Soon after civilization improves, the people will offer the Herb, which will cure the people of Kasandora of the plague. During the growth of civilization, the Master will receive periodic updates about the southwestern temple. After sealing the last lair, though, the Angel reports that all worshippers have been lured to the temple, and the Master must descend to protect his followers.
Marahna has a maximum population of 538.
The Master must clear this ancient temple of evildoers in order to reclaim his worshippers. The temple is rife with fiends and traps; this Act will be an, albeit short, test of endurance. The Master will have to navigate moving platforms and dodge mobile lightning traps, and contend with a couple varieties of snake monsters, and even incarnations of death itself.
Giving the Compass to the people of Marahna will allow them to find a Source of Magic as they navigate the open seas. Also, if the people didn't offer up the Magical Aura before the second Act, they will have to make the trip to the island again.