End of Time
The End of Time is where your characters are "stored" so to speak. It is the place where time travelers go when there are four or more of them in a single group. So, whenever you want to change the number of characters in your party, you go to The End of Time, and switch your party members, or just use the change members option in the meny screen.
Your characters also learn their respective elemental techniques here as well. First once you go to the room with Spekkio in it, you must walk around the room three times, clockwise. After doing so, talk to the creature and he will tell you what elemental techniques you learned. You can then bring other party members there from across time so they can learn their techniques.
You can also board the Epoch there.
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