From the first page of the PDF:
Ala'Ammar is ready to lead his army from Almraiven to liberate the oppressed slaves of Calimport and Memnon. He has invited his most trusted friends and allies to join the crusade for Calimshan's liberation.
This is a Quest adventure, which means that all characters in the party must qualify to go on the quest. To participate in this adventure, each PC at the table must have at least two Story Awards from the following list: CALI10, CALI12, CALI20, CALI21, CALI23, CALI27, CALI28, and/or ADCP29.
This is a two-round continuous-play Living Forgotten Realms adventure set in Calimshan for Adventure Levels 18 and 20 (these two ALs support character levels 15-20; however, the adventure was written and playtested with the assumption that no character would be below 17th level. We recommend playing with level 17-20 characters. Tables playing AL 18 with level 15/16 PCs may find this adventure extremely challenging).
It is recommended, but not required, that PCs play this adventure after having played most if not all of the previous Year 4 Paragon tier adventures set in Calimshan, including SPEC4-4 and ADCP4-2.