Hey there ! Here is some tips to help you survive the Deep Dungeon. Be aware that this page contains a spoiler. View it only if you're really having trouble navigating through the Deep Dungeon.
Note : The deep dungeon is accesible once you complete the battles at Murond Holy Place, just go to Warjilis Trade City and a scene will take place in a bar... never thought a female priest would be brave to punch a knight eh ? ^_^ Anyways, the way to the deep dungeon will open after the scene.
1. Use Orlandu. Deep Dungeon usually has enemies in greater numbers and higher levels than you are, so you'll need all the help you can get.
2. Get a Tiamat, same as Orlandu, possibly even stronger than him. See the Nevalska Temple battle on how to get one.
3. Bring Mustadio along, his snipe abilities will be very useful, Leg Aim will be more important here.
4. Bring any of the Panther monster group or a Red Chocobo, they have Ignore Height, you'll need it to reach some exits.
5. The exit is never located at the same place, so you might need to spend some time looking for it, search in corners or on pillars.
6. Bring Rafa along, make sure she has Move-Find Item, and you'll get awesome equipment on your trip.
7. Bring someone who can revive or heal, a person with Math Skills, White Magic Cure3,
Raise 2 and Esuna is by far the best.
Well, that's it for the tips, now for the real reason to go through the Deep Dungeon
He's the guy who has a 13th Zodiac Stone and you can learn, if you survive it, the Zodiac summon.
First of all, here are my reccomendations:
Ramza: Samurai with Kiyomori learned, this is important. Make sure he has an 108 Gems bracelet to protect from Frog and Poison.
Orlandu: Dosen't need anything, let him rip through the enemies.
Tiamat (Optional): I really reccomend having one, it would make this battle much easier.
Worker 8 (If you don't have a tiamat): Have him use Dispose work skill.
Summoner: Second ability Math Skills, Reaction ability Auto Potion, Support ability Magic Defense Up and Move-Hp up for movement ability. Make sure he/she has the best equipment available and has a 108 Gems bracelet to escape frog status.
Dancer: Make sure she stays well away from Elidibs' range and she should be ok. Slow Dance is what you should use.
Now for the battle itself:
Enemies: Elidibs (Serpentarius), 6 Apanda.
Orlandu will likely start off, have him use Lightining Stab on the nearest Apanda. The Tiamat should move close to Orlandu and use Triple Flame on the Apandas, you'll have 1 in 3 chances of hitting one, but it does 999 damage to them. Have Ramza use Draw Out Kiyomori on the Summoner and Dancer. Your summoner can safely advance, have him/her use Math Skills, any good combo Holy or Flare, make sure none of your members are targeted by this. The Dancer should use Slow Dance to slow down particurlarly Elidibs. Once you get rid of all the apandas, start going up to Elidibs. If he starts charging up something, it's Zodiac. Get your summoner in range, have Ramza use Kiyomori again to ensure his/her survival. Get that darn Byblos, the purple guy next to you, so he won't kill Elidibs when you're not looking. Once Zodiac is cast, if your summoner is still alive, chances are you'll be asked if you want to learn Zodiac, of course say yes. Now you gotta end him quickly, he'll use Poison Frog, which changes the targets into poisoned frogs, unless you've got protection ( 108 Gems ). He 'll also use Midgar Swarm, a physical attack that does up to 400 damage. Give him a taste of his own medicine by having your summoner cast Zodiac on him, the Tiamat should move close to him and use Triple Bracelet, which will do 999 damage. Elidibs has about 2700 hp.