Morpher(めたもる,Metamoru?), also known as Doppelganger, is a Job class from Final Fantasy Tactics Advance. Only Nu Mou can become Morphers after mastering five Beastmaster skills. Morphers take the forms of captured monsters in the Monster Bank. When morphed, they can use all of the skills the monster has in battle. The effectiveness of the Morpher will depend on the stats of the monsters in the bank.
Like their predecessor, Morphers are an Attack-oriented job, although they are a bit more balanced between Attack and Magic Power. Morphers actually lose a lot of the stat growths they had as Beastmasters, but make up for it by having the highest Speed of all Nu Mou jobs. This high Speed allows Morphers to activate their morphs as quickly as possible, and once that happens the rest of their stats are irrelevant for rest of the battle, as they use their monster's stats instead of their own.
For a Morpher to learn anything, they need to procure souls that are dropped by captured monsters. Hunters are the only class that can capture monsters, so it is crucial for the player to have one if they plan on raising a Morpher. Once a monster is captured, its Soul is automatically added to the inventory and then is able to be equipped to the Morpher.
Once a monster is in the Monster Bank, the player can then start raising it by feeding it items. Soon enough, they will only accept Curealls as food, and that's when they start gaining stats. Except for Dragons, Lamias, and Malboros, each monster will gain one point in every stat for every 2 Curealls fed to it. Dragons and Lamias will gain one point for every Cureall fed, and Malboros do not accept Curealls. Malboros will need to be fed Ethers and Elixirs.
During battle, after the Morpher has taken the form of a monster, he can then use all of the skills that the monster has. For Dragons, for example, if the player has a Thundrake and a Firewyrm, they can use both of those monsters skills in battle after morphing into a "Dragon". The strength of the attacks when morphed are based on the monsters' stats, so a Lv. 5 Goblin in the beginning of the game will not deal as much damage at the end.
Also, it is crucial to capture a Goblin as soon as possible because they go "extinct" fairly early in the game. Capture-able Thundrakes also go "extinct" eventually.