[?] Primarchs Overview

Primarchs are the combat units in Atlas. Each Primarch type needs to be researched first in the Primarch Tech Tree. Once you've researched it, a Check Mark will indicate that it's eligible for summoning. Keep in mind that the Tech Tree is like a "spellbook"–you will need to summon a Primarch anew after researching a higher level Primarch to gain the benefits of the new increased stats. 

There are a few rules around Primarchs:

• Only one Primarch of each type and Tier can be summoned at a time, so you cannot have two Bronze☆☆ Siegers at the same time, for example, but you can have a Bronze ☆☆ Sieger and a Silver ☆ Sieger out at the same time.
• A Primarch can only exist on the map when it has at least one Troop in its army–any Primarch with 0 Troops is wiped out and disappears/banished.
• Primarchs are summoned at whatever castle is set to their Home.
• Primarchs being summoned are still vulnerable to attack. Make sure your Home is safe from enemy Primarchs, or set it your Home to a Neutral region before summoning a new one.

Each Primarch belongs to a tier, with more powerful ones to be added in later updates. Currently, these Primarchs can be researched: