1. Exploding Critical Multiplier: the player rolls d20 again to see if the roll falls within the character’s critical range (by default a Natural 20; experienced characters may have a range of 18, 19, and 20 for example). If it does, another x1 multiplier is added to existing (totaled) multiplier. Keep rolling until the roll does not result within the critical range.
2. The first “x1” damage is the character’s normal damage, but this is the maximum value of such (do not roll).
3. For each successive “x1” remaining the character rolls his/her usual damage, including bonuses, and adds that to previous damage rolls made for this critical. Remember that Stressed Damage Dice house rule applies here. Do not roll once and simply multiply that amount! These are summed up and added to the maximized value (the first x1). This is the total damage. Yes, I know this takes longer but it is more variable and chaotic – you never know what might happen.
4. Bleeding: minimum of 1 Bleeding (1 MDC or SDC/HP per round) and an additional 1 point of bleeding per x1 critical multiplier over 2 (i.e.: x1 or x2 multiplier means 1 point of bleeding, but a x3 will mean 2 points, and x4 is 3 points, etc). An easy way to remember this is to take the total critical multiplier and subtract one from it (a minimum result of 1!), and this is the rate of bleeding. This applies only to creatures that can bleed, of course, and if the attack actually can cause damage to the creature.
5. Regeneration and Bleeding: Creatures that regenerate will cease bleeding once they have had their first regeneration action.
6. Random Side Effect: the various side effect tables as found in URMB (and perhaps other books) may be rolled on and applied. Depends on the situation and RP potential.
7. Knockdown: the percentage chance of Knockdown is equal to 1% per point of damage taken. If MDC damage is inflicted on a SDC creature, then use the converted damage amount (and vice versa). Knockdown can only occur if the attack has physical force behind it (i.e.: a laser will not cause knockdown, however a heavy burst firing machine gun on a Stick the Crazy can still knock him down).
8. Sniper weapons, that is weapons designed to be Single Shot sniper weapons adds this. All Sniper (or Assassin) weapons add +1 to the critical chance rating. That is a Sniper rifle will have a normal range of 19-20.
9. Aimed shots. Aimed shots take up 2 actions but double the critical chance of the shot.
Example: Jessie the Juicer is trying to take out a Bandit Leader. He's got his trusty JA-11 (which is a Sniper weapon). Using this weapon Jessie has a normal critical range of 19-20. Taking his time Jessie takes an Aimed Shot at the Bandit Leaders head. Jessie's critical chance is now 17-20. Jessie opens fire getting a natural roll of a 19 and nails the head of the bandit leader. Having scored a Critical hit Jessie rolls again and gets another 19. Since that's a critical hit he rolls yet again and gets a 10, with bonuses he still hits but it isn't a Critical Hit.
Now rolling damage, the first roll is maxed out, 4d6 mdc for 24 mdc. The second critical is also 4d6 but is rolled normally and Jessie gets a 5, 6, 6 and a 3. Now because 2 of the dice are maxed Jessie rolls again getting a 2 and another 6! Jessie rolls that 6 once more and gets a 1. So grand total for the damage is 24+5+6+6+3+2+6+1= 53 MD! The Bandit Leaders head and helmet vanish in a spray of super heated liquid and armor shards. Scratch one Bandit Leader.