This is a nifty little rule from Unearthed Arcana (although other people have evidently hit upon this idea independently) that should help speed up combat—especially with our large group.

Basically, rather than have the DM roll for each monster attack, the player instead rolls a defense check to see if his PC can avoid the monster's attack. If the defense check equals or exceeds the attack score of the enemy, the attack misses. The math works out the same, but now the players and their dice get to determine the outcome.

Here's how it works: Each time an enemy attacks a PC, the player rolls a defense check (1d20 + character's AC modifiers) against the opponent's attack score (12 + enemy's attack bonus).

As with other checks, a natural 20 is an automatic success and a natural 1 is an automatic failure. In addition, critical threat ranges are inversed, so low defense check rolls threaten critical.

So Mendelor, with an AC of 20 (+5 Dexterity, +2 bracers of armor, +3 shield), has a total AC bonus of +10. A typical Black-Blade trooper has a melee attack bonus of +5 and a critical threat range of 18-20 with his ruckblade. This translates into an attack score of 17. Against this trooper Mendelor needs to roll a 7 or better on his defense check to avoid getting hit. A natural 1, 2, or 3 threatens a critical, and if Mendelor fails a second defense check, the Black-Blade has scored a critical hit.

Any time a player casts a spell or uses a special attack that forces the enemy to make a saving throw, he rolls a magic check (1d20 + spell level + ability modifier + other modifiers) against the enemy's Fortitude, Reflex, or Will score (11 + enemy's save modifier) to determine success.