Push the stone to the right, all the way to the end. Pick up the Translator and place the block on the button that he was sitting on. You now have to get him safely to the book that you passed a second ago. A few waves of enemy soldiers will stand on your way and try to kill him before he can help you. Stay close to him and use high range combos (L1+!) and spells (Chronos Rage, Atlas Quake). The most difficult phase is obviously the last one, when you are facing the infamous mages again. Remember to take them out in the first place.
When the situation is under control, grab the translator and force him to read the spell by tapping O. After a short scene take The Key of the Ram from the door and open it, thus getting back to the courtyard.
Use the newly acquired key to open the door with a goat skull carving. Go forth and refill your mana bar. You will be trapped between the two moving, spiky gates. The only way to get out of here is to defeat all the enemy soldiers around. The best way to do this is to use Chronos Rage. When you succeed, go further into the next section of the palace.