Rise of the Argonauts

This requires you to complete every deed on Delphi.

You return to Delphi later in the game, so not everything can be completed the first time you're there.

The deeds are:
Find all the Herms on Delphi
Open the portal to Tartarus (Found on return to Delphi)
Have an audience with the Oracle of Delphi (Found on return to Delphi)
Pass the trials in the Cave of Doubts

Three of them are story related so you can't miss them.

The Herms are the only thing that is missable. They aren't too difficult to find but I'll list them all.

The first one is located straight in front of you once you get off the Argo.

The second is located near the end of the Cave of Doubts, but before you get the "determined" deed for completing the Trials of Doubt.

The third you can find once you've spoke to the Oracle, just to the right of her there is a path that takes you to a shrine of the God Apollo and next to it is a sort of bronze looking Herm with a bird on it.

The fourth Herm can't be accessed on the first trip to Delphi. When you do come back the Herm can be found once your party has gathered at the Gate of Despair. It is just to the left of the main bulk of your party members. Again, it is bronze looking with a bird atop it.

If there's anything you feel could be improved or just a general complaint, please tell me about it in the comments and I'll try to fix it.