Combat focus is the target a character is currently engaged in combat with. A ranged attacker can choose whoever he desires as his primary combat focus, but a melee combatant may only be engaged with one person at a time. Characters who are moving, casting spells, using psi, or who are engaged in non-combat activity do not need to have a combat focus, but can be focused on anyone they choose, thus preventing that combatant from gaining an attack bonus against them. If an unfocused combatant is attacked, the attacker instantly becomes their primary focus. If a combatant begins an attack on a character, that character immediately becomes their own combat focus (thus changing focus; follow the rules below).
Attacking a Focused Opponent
If a melee combatant decides to attack someone who's current combat focus is on another combatant, the attacker gains a success rank to their attack roll.
Attacking a Nonfocused Opponent
If a melee combatant decides to attack someone who currently has no combat focus, there is no bonus or penalty, but both combatants become one another's combat focus.
A character can choose to change focus any time they perform any action or upon being the target of an action. This normally occurs without penalty. However, if they are another melee combatant's focus, that combatant gets a free attack on them. If they are engaged with multiple targets, the target they have focus on gets that free attack with no bonus and the other opponents they are not focused on get a free attack with a bonus of +1 rank.