When it is your turn in a Combat, you may take an Action. This could be activating a Power, Attacking, dragging your unconscious friend to safety, or anything you'd like. Many Actions that do not normally require a roll will require one in Combat due to the time pressure and higher stakes. You may be able to climb a tree no-problem normally, but can you do it while the police are shooting at you?
Attacking is a popular Combat Action. Pick a target in range and specify how you'd like to hurt them, then roll. The relevant Attribute, Ability, Difficulty, and Damage is determined by your weapon, but GMs may apply a Difficulty modifier at their discretion, depending on the circumstances. Shooting a point-blank target is much easier than firing from a moving vehicle during a rainstorm.
While it is often true that the best defense is a good offense, be warned that committing to an attack can leave you vulnerable to other attackers.
A note on flavor for GMs: Oftentimes Players will specify some details about the manner in which they are attacking ("I take aim and try to shoot him in the chest," or "I slide under the creature's belly and stab upwards"). Most of the time, these can be interpreted as standard all-out attacks without additional modifiers. Certain areas of the body being more or less heavily armored are accounted for by standard Armor rules. If desired, you can grant additional damage or change the difficulty, but try to use standard attacks as often as possible. Once the roll is complete and Damage has been determined, narrate the attack based on the outcome, especially if the Player was not specific in how they wish to attack. This a great opportunity to help Players feel badass.
Quick Actions and Multi-Tasking
Under some circumstances, a player may wish to do more than one thing during a single round of combat, and there are a couple different ways this can happen, the most common being Quick Actions.
Certain tasks that are unlikely to fail and don't warrant a full Action (such as drawing a holstered, accessible weapon) can be taken as Quick Actions. These actions do not need to be rolled and merely subtract 2 dice from the rest of that round's Action (to a minimum of 0).
Other tasks might need a definitive Outcome in order to make sense (such as shooting at more than one target) or might be more complex and involve multiple Abilities (such as sword-fighting while on horseback). In this case, the player will make a single roll (determined by the GM), and their Outcome will either be distributed between the different actions, or will account for the success or failure of both tasks equally.
If a player wants to multi-task, it is entirely up to the GM how the dice are handled, whether one thing can be done as Quick Action or not.
Some actions are demanding or require a high level of focus, and thus you cannot multi-task while doing them. This includes any Power which requires an Action as a part of it's activation, but also covers some heavy weaponry such as mortars, heavy machine guns, and sniper rifles. If an action is Committed, you cannot perform Quick Actions in the same round, and in some cases your movement may be limited as well.
Can you think and act at the same time? Not really, it turns out. Whether or not Mental actions require a roll is largely up to GM's discretion, but generally any concerted thinking ("What do I know about this creature?", "How can I solve this door puzzle before the scarabs eat us?") is treated like a standard Action. Sometimes general awareness or "passive" mental actions (does the player notice the shark swimming up behind them?) can be rolled with their own pools without subtracting from the rest of the Action.
Characters may "hold" their Action by specifying an Action and a Condition under which the Action will occur. For example, they may say "I want to shoot the first person who turns this corner." or "I will slit the hostage's throat if they struggle." or "I will follow Jennifer and stab anyone who tries to attack us."
Characters may make a Reaction, even if they are currently holding an Action.
A held Action lasts until the Character's next Action, but actually following through on a held Action will use up the current round's Action, regardless of when the Action was originally held. For example, Jeff declares "I will pull the lever on the electric chair if the convict starts to turn into a werewolf." The current round ends and the next round begins. The convict (whose initiative puts their turn before Jeff's) then begins to sprout fur and fangs. Jeff can pull the lever, but doing so will forfeit the current round's Action.
Held Actions resolve before the Action that triggered them unless the triggering action is the firing of a firearm. Firearms cannot be reacted to without Powers.
Reactions allow a Character to take their Action before their turn in reaction to another event. Reactions are almost always defensive moves of some kind.
If a Character has already used their Action for the round, they cannot perform a Reaction, so be careful when making all-out attacks. Likewise, doing a Reaction will "use-up" the round's Action, essentially putting one Character on the defensive.
Characters cannot React to Firearms attacks without a Power.
Types of Reactions
The three main Reactions are Dodging, Defending, and Clashing.
To dodge an attack, roll Dexterity + Athletics. The Outcome of the dodge roll is subtracted from the Outcome of the attack roll, and the new Outcome determines whether or not the attack is successful. This means that ties go to the defender (as the Attacker's Outcome has been reduced to 0 in that case).
As always, the standard Difficulty is 6, but GMs may increase or decrease it depending on the situation. If you are laying on your back, it may be more difficult. If the attack is slow and ponderous, it may be easier.
Characters may also "Evade" with their primary Action on their initiative. Make a Dexterity + Athletics roll, difficulty 7. The Outcome of this evasion roll can be divided up and spread around to any income attacks, subtracting from their Outcomes. For example, if you get an Outcome of 3 on your Evade roll, and two attackers each have Outcomes of 2 on attacks against you, you can subtract 2 from the first attacker, bringing their Outcome to 0, but do not have enough left over to reduce the second attacker's Outcome down to 0. You will evade the first attack but be hit by the second.
Characters may Defend against an incoming melee attack with their own melee weapon. Defending in this way uses their weapon's standard attack roll and difficulty. The Outcome from the Defense roll subtracts from the Outcome on the attack roll, and the new Outcome determines whether or not the attack is successful. This means that ties go to the defender (as the Attacker's Outcome has been reduced to 0 in that case).
Characters may also Defend against hand-to-hand (Brawl) attacks with a melee weapon or with their own Brawl roll. Defending against Brawl attacks with a melee weapon is usually done at -1 Difficulty. A defender wielding a melee weapon may choose whether they want to Defend with their weapon or with their own Brawl roll.
Characters may Defend against attacks made on other Characters if they are within range.
Clashing is type of a high-stakes Reaction that gives the defender a chance to deal damage back to their attacker. The rolls and matchups are all the same as Defending, but instead of subtracting Outcomes from one another, both Outcomes are compared, and the Character with the higher Outcome deals full damage to their opponent. In the event of a tie, both characters successfully deal full damage.
If you have already spent your Action for a given Round and have not Exerted yourself, you may Exert your Body to React to an incoming attack. Your next Action is performed at a -2 Penalty.