You can hunt monsters, Archdevan, Argonian Camp/Castle in the field.

Please check out the differences below.

[Monster]

Monsters can be attacked only by individual armies.

Monsters respawn regularly, and you use 'Search' function in the field to hunt specific level monsters.

It requires to use AP for hunting monsters, and you can obtain various items such as Commander Equipment materials.

If you hunt Lv. 31 or above monsters, you can obtain 'Essence of Arborea', which is needed for upgrading to Lv. 31 or above Training Center, at a certain chance.

[Archdevan]

Archdevans can be attacked only by individual armies.

Monsters respawn regularly, and you use 'Search' function in the field to hunt specific level Archdevans.

There are free chances given for suppressing Archdevans daily  and you can obtain various items for upgrading/enchanting hero weapons.

▶ If you used up the number of suppressing Archdevans given, it can be reset with Crystals.

[Argonican Camp/Castle]

Argonian camps and castles can only be rally attacked.

You can obtain Argon Stone from defeating Argonian Camp and obtain Argon Core & Common/Great Argon Coins from Argonian Castle.

But, if the Main Core slots are fully occupied, Argon Stone/Core will no longer be obtained.

If you purify obtained Argon Stone/Core in Main Core, you will be able to obtain various items and key items needed for upgrading Main Core and Battle Hall.

Common/Great Argon Coins can be used at [Trade Ship] > [Argon Shop] to purchase various items. And, Blessing of Velik needed to upgrade Lv. 31 or above Headquarters can be purchased with Great Argon Coins.