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House Rule: Critical Success and Failures - D20

 
House Rule: Critical Success and Failures - D20

House RulesPlease note that these options below are house rules. They were created for D20 Modern/Future/Cyberscape, but with minimal input they can be customised for standard D20 Modern and D&D.
Further rules are available to cover a more realistic gaming experience in D20 Modern. Redirects will be listed here for those rules.

P.S. This document has not been copywrited/protected, so use and change it all you like.


Critical Successes and Failures


1.- Definitions of Critical Success and -Failures


Method of working out critical successes
A roll of a 20 on a D20 on an attack, a save, a skill, or an attribute check always threatens a critical failure. To check if it is indeed a critical success, the D20 has to be rolled again with the following outcomes:

If the second roll, with all the relevant bonuses is a failure then it is an ordinary success.
If the second roll, with all the relevant bonuses is still a success, then it is an critical success.
If the second roll is also a 20 it is always a critical success

Method of working out critical failures
A roll of a 1 on a D20 on an attack, a save, a skill, or an attribute check always threatens a critical failure. To check if it is indeed a critical failure, the D20 has to be rolled again with the following outcomes:

If the second roll, with all the relevant bonuses is successful, then it is an ordinary failure.
If the second roll, with all the relevant bonuses is still a failure, then it is a critical failure.
If the second roll is also a 1 it is always a critical failure



2.- Effects of critical attack successes and failures
Keep in mind that some actions are not as likely to cause critical failures and some have less impact then others.

Critical attack successes
For critical hits the initial damage is multiplied by the weapon’s critical hit multiplier before the armour’s damage reduction is subtracted from that damage. The damage is then applied at the following body location (roll D20, if the rolled part of body is behind cover, reroll – repeat as required):
* 1,2,3 right Leg, 4,5,6 left Leg, loss of movement = 1/2 movement for one leg or 1/5 movement if both legs are hit; if Massive Damage = replacement required plus only able to crawl while prone (1/10 movement).
* 7,8 right Arm, 9,10 left Arm, loss of balance = -3 to Dex for one arm plus -3 to Str is both arms are hit; if Massive Damage = -3 to Dex for one arm plus -3 to Str is both arms are hit plus replacement required
* 11, 12, 13, 14, 15 Torso: internal bleeding = -1 HP/round; if Massive Damage = -2 HP/round plus organ implant required
* 16 right Foot, 17 left Foot: delicate structural damage. Foot cannot be used until healed; if Massive Damage = replacement required
* 18 right Hand, 19 left Hand: delicate structural damage. Hand cannot be used until healed; if Massive Damage = replacement required
* 20 Head: sensitive area & double weapon's critical hit multiplier; if Massive Damage double weapon's critical hit multiplier plus organ implant required (roll d6: 1, 2 = eyes; 3, 4 = ears, 5 = mouth, 6 = nose; but never the brain, as brain-death means the end of the character).
A treat injury skill roll of DC20 can fix the critical impact on torsos, arms, legs, feet and hands but not any additional impact due to Massive Damage.


Ranged attack failures

Missile weapons (Roll D10)
A jam can occur with all missile weapons, including a slip, knotting or break of a string, a jamming of a firing mechanism, squashed and/or distorted ammunition, and short-circuit of power-source/battery, amongst other things.
1. - or lower: You slip and tumble and the weapon slips in your hands, your full attack hits a friend, roll for damage on a random friend (including yourself). REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
2. Any weapon is jammed for 1d4 rounds
3. Single shot weapons are jammed for 1 round, semi-automatic and automatic are jammed for 1d4 rounds
4. Single shot weapons and semi-automatic are jammed for 1 round, automatic are jammed for 1d4 rounds
5. Any weapons is jammed for 1 round
6. The weapon slips in your hands, a single ricochet missile hits a friend, roll for damage on a random friend (including yourself)
7. The weapon has been dropped before it could be used this round.
8. You slip and fall to the ground. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
9. The weapon only shoots 1 projectile this round (no multiple attacks, burst, full automatic, or double tap etc…).
10. – or higher: No critical effects.

Thrown weapons or natural ranged weapons failures (Roll D10)
1. – or lower: You slip and tumble while single missile hits a friend, roll for damage on a random friend (including yourself). REF vs DC 15 to stay upright. (If you are already prone, this has no further effect).
2. The weapons breaks/crumbles before you can use it.
3. You miss so badly that the weapon breaks/crumbles on impact.
4. You slip and fall prone to the ground before you manage to use the weapon. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
5. You drop the weapon due to sweaty hands.
6. You slip and fall prone to the ground after you manage to use the weapon. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Area effect weapons failures (Roll D10)
Area effect weapons include breath weapons, grenades, flame throwers etc.
1. – or lower: You slip and tumble while single missile impacts the largest possible number of friends or lands in the area effecting the most number of friends, roll for damage on a random friend (including yourself). Enemies are not excluded. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
2. You slip but manage to remain upright while a single missile impacts a friend or lands in the area affecting a friend, roll for damage on a random friend (including yourself). Enemies are not excluded.
3. You forgot to take the weapon off safety, it did not go off.
4. The weapon is jammed for 1d4 rounds.
5. You slip and fall prone to the ground before you manage to use the weapon. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
6. The weapon is jammed for 1 round.
7. You slip and fall prone to the ground after you manage to use the weapon. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
8. No critical effects.
9. No critical effects.
10. or higher: No critical effects.

Melee attacks failures

Melee weapons (Roll D10)
1. – or lower: Dust/Radiation/Tears block your vision, your full attack hits a friend, roll for damage on a random friend (including yourself). You’re blind for 1d4 rounds.
2. Weapon is jammed in to an obstruction. STR vs DC [Your strength] to remove (ie: with STR of 16, this would be D20+3 vs DC 16)
3. The weapon slips from your hands, a single attack hits a friend within 20 feet, roll for damage on a random friend (including yourself). The weapon lands at the feet of the victim of this attack.
4. You slip on the ground and your weapons arm swings wild and hits a friend within reach, roll for damage on a random friend (including yourself). REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
5. Your clumsy antics allow your opponent an attack of opportunity (unless he has already used them).
6. You slip on the ground and fall prone. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
7. The weapon has slipped out of your hands before it could be used this round.
8. The weapon has been knocked out of your hands due to a hard block, after it was used this round.
9. You opponent is stunned by your incompetence and misses his next attack.
10. – or higher: No critical effects.

Unarmed combat or natural melee weapons failures (Roll D10)
1. – or lower: You slip and fall and sprain you ankle. FORT vs DC 15 to avoid ½ movement. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
2. You accidentally scrape your self across the eyes in a bizarre move. You’re blind for 1d4 rounds.
3. Your clumsy antics allow your opponent an attack of opportunity (unless he has already used them)
4. Due to a lack of concentration you hit/twist at an odd angle. You take the damage you would have dealt.
5. You spin around so fast that you lose sight of your enemy. You’re flat-footed for the next round as you get your bearings.
6. Your wild back-swing with the elbow hits a random friend in an adjacent square. (If there is no friend in an adjacent square, this has no further effect).
7. You slip on the ground and fall prone. REF vs DC 15 to stay upright (If you are already prone, this has no further effect).
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.


Modifiers (Combat):
1.- For every 5 ranks you have in your Base Attack Bonus, you can add 1 to the D10 Effects roll.
o The better you are at something, the less likely you are to fumble seriously
2.- If the weapons used during the failure is of old manufacturing, then subtract each Progress Level difference from the old weapons manufacturing era compared to campaign’s current technical maturity from the D10 Effects roll.
o New technology is more reliable than old technology.
3.- By spending an action point, critical failures can be avoided.



3.- Effects of critical attribute or skill successes and failures

Critical success on attribute or skill rolls
For skills only, you gain 10% towards a miscellaneous bonus point on that specific skill.
For attribute rolls, your GM is encouraged to add spice to the success.

Critical failures on attribute or skill rolls

Strength roll and strength skill failures (Roll D10)
1. – or lower: You haven’t warmed up properly before performing the exercises. You strain a muscle reducing your strength by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
2. Stiffening in the muscles reduces your dexterity by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
3. You hyperventilate and run out of puff, and you are unable to perform any strength based activity for the next 2 minutes
4. You get a cramp in the muscle and intense pain causes you to become nauseated for 1d8 rounds. You have to seize all strenuous activity.
5. You sprain the muscle most necessary for the current action. Any strength action will take you twice as long as normal to perform for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Dexterity roll and dexterity skill failures (Roll D10)
1. - or lower: You haven’t warmed up properly before performing the exercises. Stiffening in the muscles reduces your dexterity by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
2. You strain a muscle reducing your strength by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
3. A sudden ear infection reduces your balance and makes you dizzy. You cannot perform a dexterity based activity for the next 2 minutes.
4. Sweat from your concentration washes dirt in your eyes. You are blind for 1d8 rounds as you try to clear your vision.
5. Your nerves are on edge and a twitching in your muscles causes you to have to slow down. Any dexterity based actions take twice as long as normal for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Constitution roll and constitution skill failures (Roll D10)
1. - or lower: You are set upon by new strain of pneumonia that has killed a lot of your anti-bodies. Additional effects include sore skin, thin blood and the shivers. It has been brewing for a while, but really hit home right now. Your constitution is reduced by 3 for the next 24 hours. Treat Injury (with Anti-biotics) DC 20 to reduce effects to 6 hours.
2. Your body's sudden weakness in the circumstances has shattered your confidence due to panic about your mortaility. Your wisdom is reduced by 3 for the next 24 hours. Knowledge [Earth and Life Sciences] or Sense Motive DC 20 to reduce effects to 6 hours.
3. An extra heavy nosebleed and a case of the piles have set on during your activities. Broken blood vessels during such strenuous activities are not unknown. You cannot perform a constitution based activity for the next 2 minutes.
4. A wracking sneezing attack is disrupting your body's composure. Your body is out of control for the next 1d8 rounds. You also generate quite some noise.
5. Constant itching has set in and it is driving you to distraction. All constitutional activities take twice as long as normal for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Intelligence roll and intelligence skill failures (Roll D10)
1. - or lower: A burst blood vessel in your brain causes a nervous twitch, along with slight amnesia for intelligence based actions and knowledge reducing your intelligence by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
2. The stress of the situation has overheated your brain and along with an instant migraine your temper flares and you abuse everyone in sight. Your charisma is reduced by 3 for the next 24 hours. Knowledge [Earth and Life Sciences] or Sense Motive DC 20 to reduce effects to 6 hours.
3. Depression sets in. How could you be so stupid and not be able to do as required? Your depression is debilitating for 2 minutes during which your self-esteem stops you from perform further intelligence based actions.
4. A sudden insight hits you between the eyes and there is a moment of dizziness as the awful truth shocks you to the core. Then you realise that there is a flaw in your insight, and the world is not going end after all. You are stunned for 1d8 rounds.
5. An annoying but critical thought is at the tip of your tongue, trying hard to come out, but a cheap tune you heard earlier keeps sliding up from your subconscious blocking the thought from coming out. Your brain is immersed in trying to capture the thought and loosing the tune. All intelligence based activities take twice as long as normal for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Wisdom roll and wisdom skill failures (Roll D10)
1. - or lower: A sudden panic attack, induced by stress has weakened your resolve. Your wisdom is reduced by 3 for the next 24 hours. Knowledge [Earth and Life Sciences] or Sense Motive DC 20 to reduce effects to 6 hours.
2. Mind over matter is breaking down. The mind has serious trouble controlling matter, specifically the body. Your constitution is reduced by 3 for the next 24 hours. Knowledge [Earth and Life Sciences] or Sense Motive DC 20 to reduce effects to 6 hours.
3. Low confidence sets in. How could you be so egotistical and not be able to do as required? Your lack of confidence is debilitating for 2 minutes during which your self-esteem stops you from perform further wisdom based actions.
4. Your continued failure to perform has generated a major short-term identity crisis. You are confused for 1d8 rounds.
5. Your failure to perform is distracting you as you are trying to rebuild the situation in your mind to focus on where you went wrong in order to rebuild your confidence. All wisdom based activities take twice as long as normal for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Charisma roll and charisma skill failures (Roll D10)
1. - or lower: An allergy induced rash has appeared all over your body. Swelling of the lips gives your speech a lispy tone. Your charisma is reduced by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
2. Controlling your feelings bottled up inside you, whether they are fear, anger, hate or love, is making you tense. Thinking and remembering becomes a chore. Your intelligence is reduced by 3 for 24 hours. Treat Injury DC 20 to reduce effects to 6 hours.
3. Dyslexia effects your brain and the words you want to say come out in a mangled mess along with some spluttering and drool running down your chin. Collecting yourself and straightening yourself out means you cannot perform any charisma based activities for 2 minutes.
4. Your failure to act decisively was hilarious and has made you laugh. This builds up in to an uncontrollable giggle. Soon you are bent over holding your stomach laughing at the humour of the situation for 1d8 rounds (similar to nauseous).
5. The pressure to perform has made you break out in a sweat. Along with this profuse sweating and body odour, your have lost your cool. You concentrate with each step you take to get stop perspiring and regain the mojo. All charisma based activities take twice as long as normal for the next 10 minutes.
6. Skill only: You stuffed up so badly that you could not help and learn something from your mistakes. 10% towards you next skill point.
7. No critical effects.
8. No critical effects.
9. No critical effects.
10. – or higher: No critical effects.

Modifiers (Skills only):
1.- For every 5 ranks you have in your skill, you can add 1 to the D10 Effects roll.
o The better you are at something, the less likely you are to fumble seriously
2.- If the equipment used during the failure is old, then subtract each Progress Level difference from the old equipment compared to campaign’s current technical maturity from the D10 Effects roll.
o New technology is more reliable than old technology.
3.- By spending an action point, critical failures can be avoided.


4.- Effects of critical saving throw successes and failures

Critical Success of Reflex, Fortitude and Will Saves
You gain 10% towards an miscellaneous bonus point on your saving throw.

Critical Failure of Reflex, Fortitude and Will Saves
All variables in the description of the effect of the failed safe are doubled.

Modifiers: (Roll D100 - %)
1.- For every point you have in your total bonus for your saving throw roll (ie: what you add to the D20 when you failed the roll), you have an equal cumulative percentile chance of avoiding the critical effect. (eg: if your saving throw was D20+12, then there is a 12% chance of avoiding the critical effect).
o The better you are at something, the less likely you are to fumble seriously
2.- By spending an action point, critical failures can be avoided.

Reducing the ability scores of characters with low abilities will kill them- poor Bob the Ogre Barbarian only needs to make one bad intelligence critical failure roll to become comatose from overthinking.

Perhaps a -x to rolls using that ability, instead of taking away from the ability score itself?

10%-30% chance of crit. fail. negation

Looks like this would add lots of quirky flavor to a game.

My main question is:

As I read it, the crit. failures, with their subsequent 1d10 roll, result in a 10-30% negation of the critical failure result. Nothing bad happens despite the two bad rolls.

Conversely, there's no 10-30% chance of critical hits becoming ordinary hits. (unless you've nicked armor of reinforcement from a hapless DnD character)

My house rule would be to avoid inconsistency: a critical success always does something useful, and likewise a critical failure always causes trouble.

My auxiluary question is also related to consistency:

Crit damage often results in more than 10% efficacy to the hurt caused by the weapon. Same too for skill crits?

For a critical skill success, why not just roll another d20, and add the results to the first 20, a la earthdawn or L5R. This lets you hit large DCs, and d20 Modern often increases the results of a skill based on the margin of success.





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