Final Fantasy Tactics

13th Zodiac Stone
Go into the Deep Dungeon (Found in Chapter 4, in Warjuliis Trade City). After you defeat the final boss, a Byblos will join your team. he has awesome abilities and the 13th Zodiac Stone.
Duplicate Weapons
Set the Ninja "Two Swords" skill on anyone. Equip a shild in their right hand, and the item you want duplicated in their left. Now, go to a shop that sells the items you want duplicated, choose "Best Fit" and buy them. Next, go to the formation screen and remove the items. You should now have two of the item you had in the left hand.
Instantly Kill Undead
Simply throw them a pheonix down.
Zodiac Stones
Aries, acquired after defeating Wiegraf
Taurus, found hidden in Goug Machine City
Gemini, acquired after beating Duke Elmdor in Limberry City
Cancer, acquired after beating the steel giant.
Libra, in the pssession of thunder god Cid.
Scorpio, acquired after beating Draclau.
Sagittarius, the high priest gives this stone to Meliadoul.
Capicorn, acquired after beating Dycedarg.
Aquarius, found in the deep coal mine in Goland
Pisces, given to Alma by Izlude while he was dying.
Leo, Elidibs has it in the last deep dungeon level.
Virgo, Altima possesses the last stone in the graveyard of Airships.
Hard to Get Items
Easy way to get all those hard to get items is to first train a mediator to level 8. Invite some of those hard to find monsters like Hydra's and Tiamats. Once they join you, let them breed. Take the babies into battle and have all the remaining members have Secret Hunt equipped. Now kill the babies to get some hard to get weapons.
Get Most Powerful Sword
Invite a Morbol or Ochu. The plant things with tentacles in the swamp. Breed them until the 3rd stage and poach. You should get access to a sword at the Fur Shop wich is the most powerful in the game.
Easy Kill
An easy way to kill bosses once you have Beowulf in your party is to utilize his Drain ability with his sword. You can take off an average of 800 hit points an attack. Orlandu's Lightning stab levels off almost all opponents.
Get the Zodiac Summoning
In order to get the Zodiac Summoning you must first have a summoner present on the 10th level of the dungeon and withstand a summoning of the Zodiac which does approx. 300-500 hit points an attack. You must survive and then you will have access to the magic which sucks up 99 magic per spell.
Deep Dungeon
In order for you to progress through the Deep Dungeon, you must have your characters equipped with the move-find item. you must have one of your characters land on the tile which has a switch on it. The tile is never the same so it is trial and error.
Defeat Balk
A cheap way to defeat Balk the engineer on the second last stage is to bring Worker 8 with you. The Hydra's and Tiamat's TRI attacks do not effect him in the least so his Dispose attack can do its magic from almost any place on the map.
Break Weapon
Starting the second chapter, on all bosses utilize the Break Weapon technique to eliminate any threat of special attacks. Any human boss has a weapon attack. Once broken, they are usually just left with a fist attack which is more like a scratch.
Master the Squire
Equip the monster skill to Ramza before fighting Celia & Lede after they've become Altima Beasties. Wait for them to attack you with their Ultima spell. If you survive their attack, you'll gain access to the all powerful ultima.

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 Final Fantasy V