DISCLAIMER: I may forget some of them. This list will be filled progressively as the novel accumulates chapters.

Feelless: Also known as soul power exhaustion. A state in which someone is paralyzed and cannot feel his/her body.

Indigo: A blue fruit with a balance of sugary and salty taste can grow almost anywhere in Iris.

Mana core: A core devoid or soul.

Soul core: A core containing soul, soul power, and mana that can be found in living beings able to use mana (almost everyone really).

Memory bead: A bead containing the skill and/or knowledge left by someone.

Oath Pact: A contract of sorts engaging two parties' souls until the closes are respected.

Dullahan: Empty armors capable of executing basing fighting moves and orders. Used on the frontline and also for training.

Brum leaves: Leaves of a plant that are smoked to relax the mind.

Fog: A beverage that messes with the mind. Brewed using Brum leaves and additives to create an alcoholic drink.

Inventor: none yet

Boom balls: Basically grenades lol.