This DLC includes:

Goddess master
5 missions
Pyramids environment
3 Sarcophagi to choose from when getting a Promotion
10 Mummies monsters
3 traps including 1 rare trap playable with all masters
5 artefacts
Free content for everyone: 2 new monsters & 2 new traps!

More details on the official game page of Legend of Keepers: Return of the Goddess ...