Sephiroth may serve as Final Fantasy 7's big bad, but the silver-haired super-soldier is far from the toughest boss in the game. That accolade is shared between the title's two optional super bosses: Ruby and Emerald Weapon. Defeating them is going to take some doing, though can be simplified quite a bit with a little bit of planning.
Though Ruby is widely considered to be the more challenging of the pair, Emerald Weapon is certainly no walk in the park. With a mind-boggling one million HP, no enemy in Final Fantasy 7 comes close to matching it when it comes to durability, and its offensive arsenal is equally impressive. Even so, it can be defeated relatively easily with the right strategy.
How To Prepare For The Battle With Emerald Weapon
The first big obstacle to overcome is the 20-minute time limit that's imposed on the Emerald Weapon boss fight. It is possible to beat the super boss within this window, but it's best not to risk it. Players should therefore head to the Junon Underwater Reactor and look for an enemy called Ghost Ship. They'll be able to use the Morph command to turn it into a Guide Book, which can then be traded with the Kalm Traveler for an orb of Underwater materia which will remove the time limit when equipped.
Many of the strategies for defeating Emerald Weapon require a lot of grinding to increase each party member's stats, but it's actually possible to take the boss down without too much effort. That said, for this strategy to work, players will need to obtain a Gold Chocobo, either through breeding or defeating Ruby Weapon. This will allow players to get their hands on the Knights of Round materia, which can then be paired with an orb of HP absorb materia so that it completely refills the user's HP each time that it's used.
This alone can make the battle considerably easier, but, with a little bit more work, it can become straight up easy. To remove all challenge, players can master an orb of Counter materia and pair it with Mime, then equip the W-Summon materia. If needed, players can equip HP Plus and Magic Plus materia to increase their main attacker's HP to 9,999 and boost their Magic stat, though should bear in mind that Emerald Weapon has an attack that deals 1,111 damage multiplied by the number of materia equipped. This means that having more than eight materia on a single party member will lead to them instantly dying whenever this move is used.
As for who serves as the main attacker, Knights of the Round's damage calculation is based on the user's Magic stat, so Cloud is the best choice assuming that no Magic Sources have been used up to this point. On the subject of Magic Sources, players can Morph the Unknown 3 enemy that's found in the research and cargo rooms of the Gelnika wreckage to obtain more of them and boost their primary attacker's Magic stat, but this isn't really needed. The other two party members aren't going to be doing much during the battle and will likely be dead before it ends, so their Materia doesn't matter providing one of them has the Underwater materia equipped.
How To Beat Emerald Weapon
Once ready, players should board the submarine and crash it into Emerald Weapon, which can be found swimming around near the underwater reactor. As soon as the battle begins, players should use the other two party members to throw a Hero Drink or two at the primary attacker. This isn't essential, but will speed things up a little. Next, they'll want to have their primary attacker use W-Summon and choose Knights of the Round twice. After this, they can simply sit back and watch the fireworks.
It's important that players don't do anything after casting Knights of the Round, either with the main attacker or the other two party members. Assuming that no other attacks and no items are used, the primary attacker should now respond to each of Emerald's attacks with two Knights of the Round casts, both of which will completely refill their HP.
As none of Emerald Weapon's attacks will be able to deal more than 9,999 damage and the primary attacker's HP will always be refilled after each of Emerald's attacks, it's impossible to lose with this strategy, although the other two party members will all but certainly die. It shouldn't take more than around 15 minutes for the fight to be over, but there's a little bit of variance here depending on the main attacker's level and Magic stat.
An Alternate Strategy For Beating Emerald Weapon
For those looking for a strategy that doesn't involve the Knights of Round materia, it's possible to exploit the All Lucky 7's mechanic by equipping each party member with exactly two orbs of materia and getting their HP to 9,999. Cloud, Barret, and Red XIII are good candidates for this as their HP is innately high, though assuming the party is fairly well-leveled, players should be able to reach 9,999 with any party member by equipping an orb or two of HP Plus materia. They should then enter the battle with full limit break gauges and unleash their limit breaks as soon as the battle begins.
After using all three limit breaks, players should focus on keeping the entire party's HP at 9,999 until Emerald uses its Aire Tam Storm attack. Assuming everybody's HP is full when the move is used and they each have only two materia equipped, all three party members should now be on 7,777 HP which will trigger the All Lucky 7's state. At this point, the party will take turns unleashing a barrage of 64 regular attacks and, assuming they each have their Level 4 limit breaks equipped, can add a further 43 hits to this total by using them at this time.
Every single one of these hits will deal 7,777 damage, for a grand total of 832,139 damage. Depending on how much damage the party dished out prior to Emerald using Aire Tam Storm, the super boss will likely be defeated after the All Lucky 7's state ends. If not, players will simply need to keep their party alive long enough to whittle down the boss' remaining HP. It's worth noting that this isn't a surefire strategy and may take a few retries to work, but it's still a great method for defeating Emerald Weapon without the need for excessive grinding or the Knights of the Round materia.
The Reward For Defeating Emerald Weapon
Once Emerald Weapon has been defeated, players will be rewarded with a special item called the Earth Harp. They'll be able to take the harp back to the Kalm Traveler, who will offer to trade it with them for a complete set of Master materia. These special orbs grant the user access to every spell, Summon and command in the game while only taking up a single slot, making them some of the very best materia in Final Fantasy 7.