Hello. I've been looking into the Lockdown system, and found out that it is incomplete. The guardian functions as a tank as well as a support, the recon functions as a support as well as damage, and the striker the foundation of damage. I've seen people going guardian NOT for the function of the guardian, but just because they have a shield. I also believe that supports are not found in the game often. So here are my ideas:

The Knight:
The Knight will be using the same shield that you have in your loadout, so you actually have a use for it. This will make Swiftstrike, Scarlet, Thorn Shields very useful. In addition, you will get a damage bonus low for this class. The idea behind the Knight is a balanced character with damage as well as survivability. The Striker will still be the king of damage, and the Guardian the ruler of defense, but still you get my drift.

The Medic:
The Medic is a full on supporter in the game. For the shield ability, the Medic will heal all friendly allied units by a certain amount. However, the cooldown for this effect is quite long, so it will take a lot of skill to time it. Also, each Medic in the team will increase the hit points of every person there by a small amount. This will make Medics very valuable to have. However, Medics are hit with a damage reduction low, as well as a health debuff so it's very balanced.