Combat is a fairly specific sort of conflict within the mechanics, and this section is designed to elaborate on the sort of consequences you can expect from combat encounters. The first half of this will recap the opposed rolls rules and their application in combat situations. The second half will explain the sort of consequences one can expect from engaging in this sort of conflict.
I. Resolving Combat:
When a combat encounter begins, attack order is established by an Agility check of every character present. This order is locked in until the end of the encounter (or, if the GM prefers, a combat order can be rolled before an event and retained for the duration of an event). When a character's turn comes up, they declare their target and any special actions they are taking (throwing a grenade, etc.), then roll the appropriate combat skill (Ranged Weapons or Simple Weapons). The target rolls their Defense skill, and if they tie or surpass the attacker's roll, they take no damage. If they fail, they lose Health. Health typically goes down in increments of one, but more powerful weapons or particularly brutal entities can hit for more than that.
Obviously, it is possible to die as a result of engaging in combat. If a character is reduced to 0 Health in combat, that character is incapacitated and automatically fails any defense checks. If a character is reduced to below 0 Health, that character is dead. Mental attacks work similarly: if a character is reduced to 0 Mental Health, that character is a burbling mass of psychoses subject to the whim of whatever it is that is attacking psychically. Under such circumstances, a character likewise automatically fails any defense check and is rendered permanently insane or simply braindead from the next mental attack.
Beyond death, though, combat can have serious, long-term consequences. Reduced Health generally counts as reasonably serious trauma, but nothing that can't be treated after you return to base. Foundation medical facilities are top-of-the-line and many advances have been made in mending trauma from the research conducted by Foundation staff. In certain combat scenaries, risks of instant, serious injury are present. If an individual fails a defense roll by more than 8, a serious injury is said to have occurred. When such an injury occurs, the GM will describe the injury and explain the implications.