Here will be a short explanation or link to unique rules we take advantage of in my games.
Break Trap: You make a sunder attempt against a trap that you are aware of. This is an all or nothing attempt, it cannot be assisted or used to assist another in disarming a trap. Make a CMB check against the Disarm DC of the trap. Beating the DC by 5 disarms the trap without consequence. Beating the DC by 4 or less triggers the trap, but only you are affected. Failing to beat the DC triggers the trap as normal. Pitfalls and magical traps cannot normally be overcome in this way.
Decisive Strike: Whenever you roll damage and the result is more than half the weapons base damage then this is considered a decisive strike. For Example; a great sword deals 2d6 damage, if you roll 7 or higher on that 2d6 then you have dealt a decisive strike. This is determined before any other damage bonus' are added in. Sneak attack, magical energy quality or any other bonus damage dice do not count towards determining whether or not an attack is or is not a decisive strike. Anything that rerolls the base damage dice may change a normal hit into a decisive strike. Some feats, spells or abilities may be modified by attacks that result in decisive strikes.
Fate – Each character is fated in some way. Fate is what binds the world to the divine plan, whatever that may be. The will of the Gods though is fickle and at times unpredictable. To represent this each character has a Fate Point each level. Fate Points do not accumulate. Whenever a character gains a level they'll gain a Fate Point unless they already have one. Whenever a character would be reduced below zero hit points or would be killed by an effect that requires a saving throw they may spend their Fate Point to either halve the damage taken or gain a +4 to their saving throw result. Fate Points are spent as an immediate action during the resolution of the effect that would kill the character. Either when the damage is calculated or when the saving throw is failed. The decision to spend the Fate Point must be made at this time before the game continues onward.
Shadowing: Sometimes a person who is not trained in stealth needs to hide. A person who is making a stealth check can share their result with another. The lower stealth participant must be actively trying to shadow whoever is helping them stealth. Both individuals must take full round actions (as opposed to move actions) and be in adjacent squares. Both individuals make a stealth check. These results are averaged and applied to both.