Arkhe has two types of energy, Pneuma, and Ousia, introduced in the Fontaine region. Depending on the explanation, it may appear complex, but it is actually very simple.
Which is Pneuma and Which is Ousia? How do I know which character has which?
Pneuma and Ousia are types of energy identifiable by their colors, dark blue and bright yellow, respectively. They are commonly used in mechanisms.
To find out what kind of energy a Fontaine character has, switch to that character and check their Vision. The glow should match the color of the energy and have the corresponding design.
Pneuma design
Pneuma glow
Ousia design
Ousia glow
In the case of enemies, it is the same way to know which one they have; Meka have a piece glowing in the color of their respective energy, and Breacher Primus will react to either when in their Stressed state.
How do I use it?
Each character has their way of using the energy; it usually is by using the character's Elemental Skill, but in other cases, like with Lyney, he uses it when firing a Level 2 charged shot with his bow, so be sure to check your character's Talents to find out which one uses their Arkhe.
How do their reactions work?
This mechanism is easy to use. Each Fontaine character and the Traveler possess one of two types of energy. Use the opposite energy of the enemy or mechanism, and it will react.
Do I need to have two Fontaine characters with both energies in my team the whole time?
It depends. If your focus is on combat in the overworld, it may be necessary to have them. However, if you are solving puzzles, they are not essential; there will always be a Pneuma/Ousia Block nearby the puzzle if it requires one.
