Reactions
#RedHack combat rounds are 30 seconds long – long enough for multiple attacks and for a sprinting PC to cover 180' or more. Each character only has one action during this time, but the additional opportunities for action are provided by reactions. These might be the biggest divergence between the rules and B/X D&D.
Each character with class levels has a pool of reactions per round based on level:
Wizards have one reaction. They aren't good at fighting. I'm toying with letting them spend it to maintain certain spells or fire off magic-missiles, rewriting some spells to utilise the mechanic.
Thieves have one reaction, but it hits hard. If they use it to attack, they deal double damage plus half their level, and may roll DEX to attack instead of STR. They can also spend it immediately to attack an unaware or surprised foe, dealing triple damage plus their level.
Fighters gain a reaction every other level, and also have special Techniques which give them additional opportunities to spend them – for example Riposte allows the Fighter to make a reaction attack against anyone who misses him in melee.
Clerics also gain a reaction every other level, but can only use them in the standard ways.
Monsters do not track their reactions per round, but simply have a chance to react to each trigger, based on HD:
| Hit Dice | 0-1 | 2-3 | 4-6 | 7-9 | 10-13 | 14+ |
|---|---|---|---|---|---|---|
| React On | 1/6 | 2/6 | 3/6 | 4/6 | 5/6 | 6/6 |
The standard ways to use a reaction, available to everybody, are:
Countermove – Maintain distance between you and an opponent trying to approach or get away from you by reacting to their move and moving with them. Intercept an opponent mid-move, keeping them from reaching a weaker ally or coveted item.
Counterattack – Attack a foe about to attack one of your allies in melee range.
Overwatch – Fire a ranged attack on a foe approaching you or moving out of cover or melee.
Opportunity – Attack a foe while they are changing weapons, drinking a potion, casting a spell, firing a bow in melee, or taking some other non-attack action when they should have their eyes on you.
Usually each reaction trigger can only be used by one character – one normal attack leads to reprisal by one reaction attack. (Reactions never trigger reactions.)
I'm thinking the best way to make this part of the flow of play would be to make reactions part of defending against an attack. The player being attacked, before rolling for defense, would call on another player to “defend me!” This would not necessarily be in-character, as the character may not have time. It's a non-diegetic mechanic, but it places the burden of remembering reactions on the beneficiary, and resolves the question of who gets to react: The first player invited by the PC to be willing and able to react.
Monsters simply roll on the table; multiple monsters roll with advantage. I'm thinking that the monster who reacts is the slowest monster who could act on the roll of the higher die – e.g. if you're fighting a dragon and a goblin and you roll snake eyes, the goblin reacts and not the dragon.
Shields
Currently a shield allows you to react to a successful hit either on yourself or an adjacent ally by rolling defense on STR and spending a reaction to avert the blow only if you succeed.
This is probably too powerful, and should spend a reaction for the attempt and not simply on success – it's already only targeting successful attacks, and it's worth a reaction to take a shot at not suffering what is otherwise guaranteed damage.
Claw Claw Bite
There's an issue with multiple attacks. Claw/claw/bite is already a wrinkle in the system because of the player-facing rolls. If six goblins attack one PC I can just say “make six defense rolls, difficulty 1.” If two gargoyles attack the same player, it's “make four defense rolls, then two more, then two more, difficulty 4.”
Add reactions to the mix, and we have the gargoyles potentially taking 8 opportunity attacks in one round. I think it needs to be one reaction per target – having multiple attacks shouldn't disadvantage a monster. So if the gargoyle claw/claw/bites a PC, that's one reaction attack; if they tail lash another, that's a second.
It's also tempting to figure out a way to make the bite the main attack and turning the weaker claw attacks into guaranteed reactions, but there'd need to be a very clear rule of thumb applicable to all classic monsters.
The Dopey Boss Monster
If monsters only have access to the normal reaction triggers, they rely on having allies around to use their reaction attacks. The dragon alone in its lair should be formidable, and reacts more often than it doesn't – if it has something to react to.
One solution might be to give monsters access to Fighter Techniques. This is more work so it would have to again rely on simple rules of thumb – one technique every 4 HD is a possibility, or simply one technique for every monster of 4HD or more. Indeed, multiple techniques would be a lot more powerful on monsters, which never run out of reactions during the round, and are probably best reserved for NPC fighters who have to track reactions.
NPC bowmen have the Archer technique by default, so a similar approach could be taken here – large and ferocious monsters like dragons might default to the Stand technique, making them dangerous to approach – they will react when you close into melee with them.