To access the Academy, you must first defeat the 'Moonlit Dragon' located on an island west of the Academy's main gate. This dragon uses frost and arcane attacks, but also a new 'Moonbeam Breath' that inflicts 'Frostbite' and 'Arcane Rot'. Once defeated, retrieve the 'Academy Glintstone Key (Nightfall)' from its corpse. Use the key at the magical barrier. Inside, navigate the rooftops and courtyards, being wary of the 'Night Sorcerers' who cast 'Night Comet' and 'Collapsing Stars (Nightfall)'. The 'Carian Knight' enemies are now infused with dark magic, making their attacks more potent. Find the 'Schoolhouse Classroom (Nightfall)' and 'Debate Parlor (Nightfall)' Sites of Grace. The 'Iron Virgin' enemies are more aggressive and now have a 'Shadow Grasp' attack that can instantly kill you if caught.
