There are 300 optional missions in Crisis Core Final Fantasy VII: Reunion. The Security Department (M6-5-4) mission can be found in the Zack, the Corporation Crusher Category.
How to Unlock Mission 6-5-4
The Security Department mission can be found under the Zack, the Corporation Crusher sub-category that you can unlock by completing all the Looking for Items (M6-1) sub-category that first unlocks in Chapter 2. You must then complete the third mission in the Zack, the Corporation Crusher (M6-5) sub-category to unlock this mission.
How to Defeat the Grand Horn
Most of the missions in this sub-category are relatively straight forward and most players will complete them as they encounter them at the start of Chapter 2. This particular mission, however, becomes a bit more challenging when you reach the at the end of it.
Before you head to the boss straight in front of you, take the time to open the four chests to obtain an , , , and a Materia. There are three chests to your left, two by the barn, and one inside the pen. The last chest will be on the opposite side, just before the monster. You may wish to consider ensuring you have Stun protection before proceeding to the battle too, as the Grand Horn will cast Gaea which can stun you if you get hit by it. Accessories such as the , , and all the Chocobo Armlet series of accessories will protect against this.
Once you start the battle, you’ll notice that the Grand Horn is accompanied by another, the ! The particular enemy can be quite frustrating as it will repeatedly cast either Flare or Electrocute on you. And if that wasn’t enough, it can use an attack called Eerie Wave that will reduce your AP.
The Grand Horn will come equipped with the Null-Physical and Null-Magical buffs. This means that it will guard against any physical or magical attack. So, how are you meant to deal damage to it you may ask? Simple, use either or as both of these ignore the buffs the Grand Horn has, and will either one-shot the enemies or leave them not far from death. You can find out where to get Ultima or Costly Punch early by going to our Ultima page or our Costly Punch page. Note: Some Limit Breaks can deal damage or even kill the Grand Horn should you not have any of the above materia.
Now that you know how to deal damage to the Grand Horn, you’ll need to know how to avoid its attacks. The worst attack it has is either its Gaia’s Wrath attack which has a large area of effect and will leave you stunned if you get hit by it or the Rotten Smell attack which will Poison, Silence, Curse, and Stun you. For this reason alone, we recommend equipping a or to counter this attack. Other than that, it has a normal attack which can deal some serious damage, but it’s slow and easy to avoid. For the Gaia’s Wrath attack, keep your distance as it slams the ground twice, or equip an anti-stun accessory. With the Rotten Smell attack, you can avoid it by simply standing away from the front of the monster.
As with most Missions in Crisis Core Final Fantasy VII: Reunion. The more time you spend powering up Zack, the easier it will become, so your experience may vary when it comes to encountering these beasts.