There are 300 optional missions in Crisis Core Final Fantasy VII: Reunion. Experiment No. 124 (M5-4-6) can be found in the Hojo’s Laboratory Category.
How to Unlock Mission 5-4-6
You won’t be able to unlock this mission until late in the game. Once you reach Chapter 10, the final chapter of the main story, you will finally unlock Mission 5-2-3: Experiment No. 109. Once you unlock that, just complete it to open up the next mission and continue doing that, until you finally unlock Mission 5-4-6.
How to Defeat Experiment No. 124
You will be up against a harder version of the Sephiroth fight (this one is called , but will be referred to as Sephiroth for easier writing), although thankfully, you don’t have to worry about him summoning the Materia here. Despite that, though, this pseudo-Sephiroth has a few more tricks up his sleeve over the story battle. He will move around rather slowly, with large movements being teleports instead. These can be very annoying, as he has a brief period of invincibility upon teleporting, before you will be able to damage him again. He will sometimes just teleport multiple times in a row, too, so there’s nothing you can really do about it.
In terms of attacks, the two biggest ones are Draw Slash and Heartless Angel. Draw Slash will have Sephiroth charge up an attack and deliver a sword slash in front of him. This attack deals damage based on your max HP, and will always put you in critical health if you’re full. As an example, if you have 99,999 HP, the attack will always deal 87,999 damage, so you will always want your health above the damage amount it does, just to be on the safe side. Note that the shockwave from this attack gives it a longer reach, so be careful about being too close to him as he’s performing it.
Heartless Angel is an attack you cannot avoid, as it seemingly goes through your guard and there’s no dodging it at all. This attack will hit you and leave you with a single HP left, so pretty much any follow-up attack will down you. However, if you manage to get lucky with a Null Physical buff, then that will block it (seems to be the only way to negate this attack). One thing you need to do is make sure to always have healing handy when you see this attack, since you want to immediately heal after taking the damage.
At some point during the battle, you will see Sephiroth use , which will heal him for 13k plus whenever it ticks. There’s nothing you can do about this, but Sephiroth’s actions can be interrupted if you attack him, so there is a chance to stop it (and the other attacks). He also has access to , which will reduce the damage he takes, as well as and . For the latter, whenever you see the screen fill with light, that is when you should dodge to avoid the damage from . His normal attack can be done four times in a row, but he doesn’t always do all four hits every time.
isn’t a bad move to use against this boss, although the constant teleporting can be annoying. You can also use magic, such as , , or even , although that last one isn’t going to be as effective as it is on larger enemies. is a great attack to use, since it doubly heals you, as well as damages the enemy. Don’t forget to keep a stock of on you, when you need to heal in the aftermath of Heartless Angel, or if you should get hit by Draw Slash.