There is one minor, but powerful, change to the Arcane Defiling rule as described in the Dark Sun Campaign Setting. Instead of declaring your intent to defile before the roll is made, you may instead declare to reroll after the fact, either your attack or damage roll, and take the second result (along with the consequences of defiling). This change adds a deeper level of temptation to defiling. If it turns out that this was a heavily exploitable idea, then the DM reserves the right to pull it at his discretion.
A party who roleplays for a period of time uninterrupted OR roleplays in a way that is appreciated by the DM can receive experience equivalent to defeating monsters of that same level.
Weapons have a chance to break when the character rolls a 1 on their attack rolls. Where this rule differs from the DSCS is that I will allow a saving throw on that roll. If that roll fails then the player will have to treat their weapon as an improvised weapon until they can get it repaired. Metal weapons, in keeping with the normal rules, will receive a +5 bonus on their saving throw (fail on 4 or lower). Update: Also, weapon breakage rules only apply with melee or close powers with the weapon keyword. So using a dagger as an implement for a ranged power will not incur weapon breakage, but an implement power with a dagger using a melee power does. For close powers, only the first attack will be counted for weapon breakage.
If the XP for a given encounter, after divvying points between players, results in a decimal number, round that number up to the nearest whole number, no matter what the decimal is. For instance, four players divide an encounter that was 397 xp, resulting in 99.25 xp per player. Make that final number 100 xp per player.