Doga's Manor is only accessible with Nautilus, which is why you have to go back to Ancient Ruins to pick it up. Then return to Doga's Manor. You'll be teleported to Doga's Grotto after entering the manor.
This dungeon is a one-time visit, so make sure that you collect all chests and bestiary listed below.
Bestiary Checklist:
There are 2 bosses here (Doga and Unei) which you have to fight one after another without a break.
Bosses: Doga and Unei
The thing about these battles is that you fight the bosses one at a time without a break, which means you cannot heal after defeating Doga. However, the battles themselves are pretty straightforward. They both can use high-level magic that can easily kill one of your party members. As long as you can keep up with reviving and healing, you should be fine.
Before leaving, open your map and check if you have 6 chests and 2 items collected.
Chests/Items:
- C-301: 20000 gil - B1 (#2), first split path.
- C-302: 20000 gil - B1 (#2), near the exit.
- C-303: Shining Curtain - B2, northwest room, lweft chest.
- C-304: Shining Curtain - B2, northwest room, middle chest.
- C-305: Shining Curtain - B2, northwest room, right chest.
- C-306: Shining Curtain - B2, northeast room.
- I-069: Eureka Key - B3, after defeating the bosses.
- I-070: Syrcus Key - B3, after defeating the bosses.