Combat

Critical Miss
Attack rolls with a roll of a 1, might cause the character to fall prone, the player will make a Balance check DC 15, failure indicates they fall prone.

Initiative Rolls
Initiative rolls will be made after each round or kept continuous at the depression of the DM.

NPC Cohorts
All mounts, familiars, and cohorts will day to coincide the players turn. Some situations might prevent this, (all in the DM's discretion).

Defense Rolls
Each time a character is attacked, he must make a D20 roll and add the characters AC modifier -10. Every attack becomes an opposed roll, with the attacker and defender matching their modified rolls against one another. NPC that attack or effect other NPC will not use this rule and instead use the standard attack roll vs. AC.

The defense roll is expressed as [1d20 + (AC -10)]. A result in a tie always goes to the defender. Ref. DMG pg 25

Weapon Size
When an attacker uses a weapon that is a smaller weapon than the defender is using, then the defender may make an attack of opportunity, before the attack is made. This opportunity attack is only available if defender is not flat footed. For opponents that have a natural weapon, use there size category to figure the size of the weapon. For example a owlbear is large attacking a human with a long sword, the Owlbear will get an attack of oppertunity, the human would not. If each opponent has the same size of weapon then neither gets an attack of opportunity for weapon size.