Instructions
Purchase Magic Tags from any of the numerous item shops that carry the item. Some item shops, such as the ones in Lindblum and Black Mage Village, will not carry Magic Tags until the third or fourth disk of the game. Magic Tags cost 100 Gil each.
Steal a Magic Tag from a Zombie, Dracozombie or Whale Zombie by using the "Steal" or "Mug" ability. Zombies will sometimes drop Magic Tags after you defeat them in battle.
Select the item menu from your battle menu when you encounter a foe. Scroll through the list of items and select a Magic Tag.
Select the party member who has the Zombie status effect with the analog stick or the control pad. Press the action button to use the Magic Tag and cure them of their Zombie status. Repeat this process until all of your party members have been cured.