Contract Completed Trophy in Mask of Mists

Story Related.

This is one of the two endings available, but the only one that doesn't require the Stone Masks to get and is not missable. After you defeat the overgrown Mushroom for One Final Step, you'll make your way to the Archmage encased in a crystal. Interact with the crystal to free him. This will finish the game and unlock the trophy.

If you picked up all the Stone Masks (and acquired the Gilded Mushroom from turning them in), you can easily get the second ending for Mask of Mists. After the final cutscenes are done for the first ending, just hit "continue" from the main menu and you'll load into the game right after you defeated the Overgrown mushroom. Follow the instructions under Mask of Mists from here to get that second ending.