Complex sentence: The god Adonna, who created Sidhedark, seems not to given its world quite as much permanence as the human world has; it is possible for beings with enough knowledge and willpower to cause temporary changes.
Split into simpler sentences: The god Adonna, who created Sidhedark, seems not to have given its world quite as much permanence as the human world has. It is possible for beings with enough knowledge and willpower to cause temporary changes.