Once you've got Erk (use Marcus' rescue command) and have fended off all of the nearby opponents at your base, it's time to start sweeping the map. Send your troops across, keeping Lowen and Oswin to ...
Here is every quest, combat encounter, and more in Original Sin's final act: Arx.
The goofy minigame is a messy trial of "don't stand in the shit," like most FF14 encounters, but the premise feels more Mario ...