(SPOILER)Nothing really. But you do get access of places, items and such (Collapse at Nabudis, Ardor at Barheim etc.) But you don't get anything really, because to get Espers, you must do other important things such as Mobs Hunt (To get Chuculainn, you must defeat White Mousse and Wraith). So you should say, Do you get anything special for getting the mobs hunt? Yes, Path for Espers.
But after you defeat ten Espers, Zodiac is now available at thee-bayHenne Mines. I guess that's the special (The LP given by Espers is also yummy
).
You get some inventory after you defeat espers:
Belias: Fragment of Dawn (Key Item and Accessory)
Mateus: Sword of Conqueror King (Key Item and Weapon)
Shumihaza: Sword of the Contract (Key Item and Weapon)
Hashmalim: Sun-Cryst (Not really)
Famfrit: NO
Adrammalech: NO but you get to travel deep within the cavern without worries.![]()
Chuculainn: NO but you get to fight Foobar which is supposed to be in Nabreus. She's cute btw. Garamsythe is clear now. In this fight, your HP will be drained like Slip/Sap, Slip/Sap-protective armor won't help you.
Zalera: NO but you get entrance to Garamsythe. Curse the 5.00.00 timer.
Exodus/ExDeath: NO. He sucked, actually. I want a worthy opponent eventhough, I lost to him more than 10 times. In this fight, you can't use item, rely on magic.
Zeromus: Well, you can fight the Dark Lord.....Beware, Zeromus (Gravity) and Dark Lord (Darkness) make a strong pair. Be sure to have a Dark-Absorbing equipment.In this fight, you can't use magic, rely on item.
Chaos: Well you actually can raise your clan rank here. (Phunbaba Boss, Fury, Deathscythe, Goliath, Loppy, Chaos Judas and Chaos). In this fight, Fight/Attack command cannot be used. Use Far Attack/Telekinesis.
Ultima: You get to travel far in Crystal Grande and obtain several useful thing. In this fight, Ultima can seal any of your command at any time.
Zodiac: I haven't fight him yet, sorry.
Espers is good way to level up. Let say Vaan, Penelo and Fran defeats a Baknamy, receiving 1000 LP.
When you fight with an Esper, you gained 3000 LP but only the summoner get it.