The goal of this is to:
- speed things up
- keep players focused
- nail down the fiction corresponding to each attack
- make monsters more interesting
- provide more risk/reward choices
When monsters miss, they provoke an opportunity action from enemies that threaten them. This action is a standard action: attack, move, whatever.
When a player misses a monster that threatens it, that monster uses its miss reaction.
You need to give monsters these reactions. By default, it could just be a damage roll, no attack roll. You do not want the potential to whiff here. If a player misses, something bad will happen.
You can vary miss effects by margin of failure if you want.
When a player attacks, ask him exactly what he's doing, how he's aiming, etc. if he doesn't say ("dunno just attacking") this module doesn't apply.
When a PC crits or hits the AC / Defense + 5 (so a 21 vs AC 5/16), the PC does just what he wanted. It bypasses hp. The effect does what it does. If he was trying to cut dude's head off, it is now rolling on the floor. If he was aiming for the troll's eye, that eye now has an arrow in it.
Ongoing Effect Module
Give monsters effects (like auto damage) that proc at the start or end of combat turns rather than rounds.
This is perfect for a zombie that has grabbed a PC and is biting at his neck. Say that the zombie is currently biting at fighter's neck. It's now cleric's turn. Cleric! What do you do!? Fighter's about to buy it! No waiting around for next round pshaw.
GM moves monsters all at once at the top of the round. They act as normal on their initiatives but do not move. In 4E terms, they use their move actions at top of round.
Players can spend a standard action to reroll initiative and take the higher result.
Weird option: when you attack, reroll initiative and take the new one if lower.
GM doesn't roll attack or damage.
Instead, when you would attack a PC and they would be aware of an able to respond to the attack, describe the attack ("the dragon's chest is expanding; his mouth is about to open"), and ask what they do.
They can counterattack or defend.
If they counter, they attack as normal.
If they hit, they do damage as normal and suffer as normal from the enemy's attack.
If they miss, they only suffer.
If they crit (or get a hard hit, DC+5), they do damage and suffer none.
If they defend, ask them how.
Based on desrciption choose appropriate defense (AC, reflex, etc).
Have them roll their defense bonus (= Defense - 10)
Against DC = 10 + attacker's attack bonus (old school: 1+HD, 4E, 5+Level)
On a hit, they evade or block as they described.
On a hard hit/crit, not only that, but they leave the enemy in poor position: PC may take opportunity action
On miss, suffer damage as normal; GM says how
If you would make an attack of which they are unaware, make it as normal but do not narrate it. The attack roll is a saving throw to avoid the effect. This bypasses hp if it hits. Suddenly a javelin is in your side.