Episode 31 - 40
Ko begins his plans to enshroud the world in darkness. Palmer and Pearl finally meet, but pearl is too angry with former for his dissapearance. Diamond and Pearl battle it out in a fierce match, but pearl wins. The thomp volacno erupts and Gabryl and Gary go investigate, finding the ancient armory and a shrine. The sun mage attacks them.
Episode 41 - 50
Tungsten saves the duo from the sun mage's attacks and engages in a heated battle. Diamond sneaks into Ko's castle and gets captured, his father decides to take the rap for him. Diamond and friends begin to find the 5 cobalt star shards to save Ubi. However, Pearl and the mages are after them too. Cyrus fights Pearl.
If you look closely, in ep 30+ there is a scene on the redux cobalt shards, they are important in the reduxion series, it will be shown after season 5 ends, and is not that related to the pokemon series. The main characters are Ruby and May.
