The first one is Argor the Dueller. It helps you in fight with enemy, by cancelling their superblow progress and preventing their magic sometimes. It can be helpful against tough enemies.
Second one is Grog the Healer. Like his name, it is a healer. It heals you, and gives you shield. We summon it mostly when we're about to die.
Targar the Protector is the third amulet summon. It's a total staller. It just stalls, and reduces damage, never attacks. It makes the fight longer, you can use it to wait for your teammates' help, or if you're really angry and want to waste your opponents' current buffs.
The last one is Xar the Executioner. He instantly finishes the enemies with 25% hp or less. And also it is a total executioner, like our 3rd profession, it mostly injures the opponents it finished off. It'd be a great help to Executioner order fights.