The third DLC for Immortals Fenyx Rising, The Lost Gods, lets you play as Ash, a new playable character. Now that Fenyx herself has become a god, she needs someone to be her agent on earth when Zeus commands that she not interfere with how things are going for mortals.
The DLC also changes up quite a few mechanics, including the save mechanic. You can no longer just save the game whenever you like and will need to make an offering at an alter to do so.
The offering in question will need to be some Figs, which can be found all over the island of Piryte, the new location that you will be playing in. After obtained some figs, players can then visit one of the main altars all over the island.
Altars will be marked on the map by golden dish icons, and players can interact with them to make an offering. One of the icons on the screen that pops up will have downward arrow, and this how players can save their progress in The Lost Gods DLC.
Figs are quite plentiful in the game, and will grow on every section of the island. As long you make sure to grab them when you can, you should always have some figs to be able to save your game at any altar you find.