Here’s how to unlock Ghirahim in Hyrule Warriors!
Like Agitha, Ghirahim can only be unlocked by completing a specific challenge in Adventure Mode. But be warned, the road to Ghirahim in Adventure Mode is much, much harder than the path to Agitha. So be sure to have a high level Fi (as you will be forced to use her in specific challenges; I’d recommend being around level 25-30) and a contingency character that can deal with enemies quickly and effectively, preferably Link equipped with the Master Sword.
Firstly, you will need to make it to the grid position marked by the red circle in the map (as shown in the image above). There are a couple of hard challenges in between your destination; including a time trial that requires you to defeat two Imprisons within 10 minutes. A high level character should help you in these challenges, but I’d recommend finding a friend to delicate objectives evenly.
Once you reach the marked position, you will need to search the grid area for the secret path to open the conditions to unlock Ghirahim. You won’t need a compass, but you will require a candle/lantern. Using the image above as an indicator to decipher what tree to burn with your lantern. Burning the correct tree will reveal a secret passage.
Now you can enter the challenge to unlock Ghirahim. This is one of the more difficult grids, so come prepared if you choose to go at it alone. You will face two enemy forces that will attack you simultaneously. Ghirahim’s forces will attack from the south and west, while the Icy Big Poe will hit from the north and east.
It is vital at the start of the battle that you maintain control of the northern area and western outpost/keeps (as marked by the red circles in the image above). I find that running to the west and taking the two outpost and the keep is vital to swing momentum in your favorite. Holding these position will keep your ally base relatively safe from raids while you are preoccupied with other objectives. Also noteworthy, Ghirahim deals massive damage with his combo’s, so be sure to have a bottle or two ready.
The battle should become easier after defeating Ghirahim and stopping his forces advancing into the Ally base. You should take this opportunity to take the keep to the east to free the fairy. In addition to that, defeating 1000 enemies will reveal a Golden Skultula located at the north east corner of the map. You will need to hookshot up to access the top where the Skultula presides. Once you are ready for victory, defeat the Icy Big Poe. Doing so will unlock Ghirahim. Congratulations!