ArcticZone Online Entertainment Support Forums

This game has the core 8 classes from the original and 6 new classes, with the original classes being deemed tier 1 classes, and the new ones being deemed tier 2 classes and upon promoting for the first time with a tier 1 class, you will be given an option to either combine with another tier 1 class, or you can continue down the same path.
If you choose to combine with another class, you will gain benefits of that class with a few penalties.

Weapons and armor not allowed in your primary class, but allowed in your secondary class will require the level of your secondary class.

Spells allowed by your secondary class will go off the level of your secondary class but will have damage penalties. Single target spells only hit at 50% damage, and area-effect spells only hit at 25% damage.
This applies to both damage and healing spells.

There are class-skill penalties as well but those will be shown to you when confirming your class selection.
As an example, a hunter tames beasts as permanent pets that level up, as a secondary hunter, your beast experience charts will be doubled and can only gain half the number of levels. this was done to allow pure classes to still hold the edge on their abilities.

Also, if you decide not to combine with another class and stay on your current class's training, you will gain an additional ability only you can get by remaining a pure class. As an example, as said above, a hunter can tame wild beasts that become permanent pets that level up, however they can only have 1 active at a time. If you are a pure-class hunter, you will be allowed to have 2 actives at a time.