There are 4 agent types or classes currently in-game:

1. Striker class: These are the melee type units, they have the lowest range and their attacks can cleave all the enemies in their area. You can recognize a Striker by the sign displayed below.

2. Gunner class: These are the mid-range units. You can recognize a Gunner by the sign displayed below.

3. Artillery class: These are the longest range units in the game. You can recognize an Artillery unit by the sign displayed below.

4. Support class: These are the units focused on enhancing your other units even though some of them can pack quite a punch. You can recognize a Support unit by the sign displayed below.

Throughout the game, you will encounter enemies that are weaker to some of the Agent types. Building your team accordingly can go a long way when it comes to overcoming a hard challenge.