Making an attack requires a major action, unless specifically stated otherwise. The attacker rolls their ATT die for melee or ranged attacks, their PRE die for most spells, or a different die if a rule so states. The target rolls a passive defense die (which does not take an action and is done even when knocked out), which is DEF against a melee or ranged attack, PRE or FOR against many spells (depending on the rules for the specific spell), or a different die if a rule so states. Only one type of defense can be used against a particular attack if multiple types are available.
A character who is unaware of an attack cannot block, parry, or dodge that attack, and their passive defense roll is disadvantaged, unless the attack is indirect in nature (poisons, mental attacks, etc.). However, a target has a minimum passive defense (with no disadvantage from any source) against ranged attacks and ranged spells with a physical effect of any kind, as the attacker always has to at least aim accurately, even against a helpless target. This minimum is based on the range, as listed under the ranged weapon tables.
BLOCKING: Blocking with a shield takes a minor interrupt action to perform. A block can be used against a melee or ranged attack, and even against spells that have direct physical effects (i.e., that are normally defended against using a DEF die). A block roll is just a DEF roll, but with advantage.
PARRYING: Parrying with a melee weapon takes a minor interrupt action to perform. A parry can be used against a melee attack (but not ranged attacks or spells). A parry is rolled using the target's ATT die, but this roll can be disadvantaged if you are unarmed and parrying a weapon, have a weapon not designed to parry with (see the equipment rules), or if you attempt to parry a giant opponent.
DODGING: Dodging an attack takes a minor interrupt action to perform. A dodge can be used against melee attacks, ranged attacks, and spells that have any kind of physical effect. A dodge is rolled using the target's REF die, but if you do not have a decent amount of room to maneuver, your roll is disadvantaged.
OPPORTUNITY ATTACKS: Taking an exclusive action, aiming a ranged attack, moving out of a region with a minor action, running into a region, trying to move directly past an enemy, or any situation stated in a particular rule, will provoke a possible opportunity attack for each enemy in the region. An opportunity attack is a minor interrupt action (so it will use up an AP from the attacker's next turn) and must be a basic melee attack (no ranged attacks, spells, or other abilities).
When a character is hit by an attack, they take a point of damage, plus an additional point for each additional success. This damage is subtracted from the character’s HPs. Note that some attacks might specify that they do something other than damage (or in addition to damage) when they hit.
KNOCKED OUT: If a character’s HPs are reduced to zero, they are knocked out for the rest of the encounter (HPs cannot go below zero). This also reduces their MPs to zero at the same time (and they cannot recover or use MPs while knocked out). After the encounter is over (or if they are revived through healing during combat, see below), and if the knockout was caused by lethal damage, the character must roll their FOR die. A roll of 1 results in death; a roll of 2 results in a mortal wound; a roll of 3 means the character is badly wounded. A roll of 4+ means the character wakes up after five minutes or more with a single HP, but they are otherwise okay (except that they are stunned for the first turn they wake up).
INSTANT DEATH: Lethal damage that does 2xHP in one shot instantly kills (or 1xHP if the target is already knocked out). Minor unnamed evil characters are instantly killed when knocked out by lethal damage (except as needed for story purposes), as are characters who have 0 HP to begin with.
MORTALLY WOUNDED: A mortally wounded character will not wake up and will die within ten minutes. If they are healed (at least 1 HP), they will go from mortally wounded to badly wounded (see below). First aid can save a mortally wounded character (healing a single HP). This takes ten or more minutes (so only one character can attempt it) and requires an INT roll with a difficulty die of D4 (D8 if you have to improvise bandages, D12 if you can’t even improvise). All adventurers are assumed to know how to administer basic first aid. Without magical healing, even if a mortally wounded character ultimately survives, they will be permanently scarred or damaged in some way, as the GM deems appropriate (can't run, missing an eye, missing a hand, disadvantage on all endurance rolls, psychological scars, etc.).
BADLY WOUNDED: A badly wounded character will wake up in about an hour (without any help, otherwise they can be woken up within five to ten minutes). Once awake, any rolls they make are disadvantaged (including defenses), their total APs are halved (round down, with 0 APs meaning only free actions can be taken), and they cannot recover or use MPs. The penalty is removed when HPs are fully restored (which takes about a week of rest for a hero, or a month-plus for non-heroes, although healing magic could work much faster).
WOUNDED: A non-badly wounded character suffers no penalties (other than being easier to knock out due to not having their full HPs) and will recover their full HPs after about an hour of rest. They can use and recover MPs normally.
MAGICAL HEALING: If a character is healed through magic while at zero hit points, they immediately make their survival roll. If they roll a 1, the healing is too late and they are dead (although powerful ritual magic could resurrect them). If they roll greater than a 1, their hit points are restored according to the ability used, but they will be stunned (unable to take actions, all rolls disadvantaged) for at least one turn. If they are mortally wounded, they are stunned for the rest of the encounter (then badly wounded thereafter) or until their HPs are fully restored (with a minimum of one turn being stunned, after which they will still have a "permanent" injury). If they are badly wounded, the normal penalties still apply until their HPs are fully restored. If a magical healing ritual is used (not just a healing spell in combat), the survival roll is advantaged. A magical healing ritual will also prevent any permanent injuries and restore them to their full HPs.
Unarmed strikes, such as punching, kicking, etc., are normal attacks using the attacker’s STR die, reduced by two die ranks, and will only do lethal damage if the target is already unconscious. An unarmed strike against an opponent who has a melee weapon will provoke an opportunity attack (before the strike is attempted).
GRAPPLING: Attempting to grab a target uses the attacker's STR die, reduced by two die ranks, vs. the defender's STR die (not reduced at all). The target could block, parry, or dodge instead, if desired. Attempting to grab an opponent who has a melee weapon will provoke an opportunity attack (before the grab is attempted).
A single success results in a partial grab (an arm, clothing, etc.). A partially grabbed target cannot move, but neither can the grappler without releasing the grab (unless they are much larger). If the target or the grappler attempts to attack anyone other than each other, their attack roll is disadvantaged. A grab can be sustained each turn with a minor action (otherwise the target is released).
A double success results in a full hold (both arms, arm behind the back, bear hug, or any more complex hold). A fully held target is disadvantaged for any physical actions or defenses. While holding a target, the attacker's own defenses are disadvantaged against physical attacks, except for those from the target, where they are advantaged. The target can be forced to the ground with a minor action or crushed (effectively an unarmed strike that active defenses cannot be used against) with a major action.
In addition to the normal actions that can be taken against a grabbed target, a partially grabbed target can be forced to the ground with a minor action. A fully held target can be forced to move one region with an exclusive action (the attacker moves with them). A fully held target can also be thrown to the ground with a major action (effectively an unarmed strike that active defenses cannot be used against, with advantage and potentially lethal if the ground is solid/rocky/has spikes/etc.).
ESCAPING: A person who has been grabbed can attempt to escape by using an action and rolling their STR (disadvantaged if they are fully held) vs. the grappler’s STR (with the normal -2 die ranks). If the target wins, they escape, but this counts as a major action and their turn is over. If the target rolls double the grappler’s roll, it is only a minor action and they can use their other actions normally. If they roll triple the grappler’s roll, their escape becomes a free action.
When fighting while mounted, the rider and mount generally act as one character (although each can be targeted separately by enemies). Use the higher of the pair’s initiatives and APs, but if the mount has more APs than the rider, those extra actions can only be used for movement. If the rider has more APs, those extra actions cannot be used for movement. While their actions are shared, the mount makes rolls for anything it does, while the rider makes rolls for what they do.
When a mount “runs”, they move three regions instead of two (unless they are an unusually slow or fast mount). Mounts can dodge for both themselves and the rider. Riders cannot dodge or make unarmed attacks, and can only parry or block for themselves (barring abilities that let them do otherwise). A mounted 1H melee attack against an unmounted target is advantaged, unless the target has a long weapon. A ranged attack from a moving mount is disadvantaged.
Unskilled riders are disadvantaged for all physical actions and their APs are halved (round down). Mounting or dismounting is a minor action (or an exclusive action for an unskilled rider).
PRONE: Any character who is not standing requires an exclusive action to crawl a single region. Physical attacks (other than those with firearms or crossbows) and any defenses against melee attacks are disadvantaged. Standing up takes a major action.
HELPLESS: A helpless character (tied up, paralyzed, etc.) cannot take any physical actions, including movement. Their DEF is automatically a D2 with disadvantage against melee attacks (or point-blank ranged attacks). Ranged attacks still have the minimum DEF based on range mentioned above.
SURPRISED: When a character is surprised at the beginning of combat, their REF roll to determine turn order is disadvantaged (along with any passive defense rolls). They will also usually not have weapons ready.