Primal Bosses" are better known as "Forgotten Warriors in DreamScape 317. It is a level 130 boss . Forgotten Warriors can be found in your Magic Spellbook - Boss Teleport - Forgotten Warrior.
In this server Forgotten Warriors aren't very hard to kill. But, it is recommended that you have a prayer level of at least 92, so you can pray "Soulsplit". You could also pray "Turmoil", which requires 95 prayer. You can kill the boss with almost any gear, you don't need any sort of special gear for it.