A new take on Critical Hits (and lasting injuries)

I wasn't really satisfied by the default package way of resolving critical hits so I decided to see if I could cook up something a bit more interesting for my current campaign. I'll give the house rule below a test run for a couple sessions, see how it goes...

There is now a DC10 CON save to avoid taking the additional damage but if you do fail, then the critical hit is not just mere damage. I think it's a good balance to prevent random crazy rolling spikes while providing an interesting mechanic beyond just "big HP loss" for when it happens, keeping the "wow shit" factor. Also, since the (CON) save is in the victims hands, it spreads the "luck" a little.

The effects of Lasting Injuries can be seen as quite severe but they are only disadvantages, which simulates I think the fact that someone else can "Help" you in a task, just like you would help someone injured. Overall, it should also provide interesting in-character action and role-play and not just be yet another game mechanic.

This rule also applies to NPC during combat, which mean a good critical hit can leave enemies at a severe disadvantage.


I use standard Weighted table to roll for hit location usually.

CRITICAL HITS
When you are victim of a critical hit

• Take the normal rolled damage. 
• Do a DC10 CON save. If your current HP are equal or above your 1/2 maximum HP, do so with Advantage. 
• On success: You suffer no lasting injury. 
• On a failure: Take the added damage from the critical and you suffer a lasting injury to the body part hit. 
• If you were knocked unconscious (<=0 HP) due to the normal damage, you automatically fail the DC10 CON save to prevent lasting injury. 

LASTING INJURIES

• Head: You suffer Disadvantage to all INT and WIS checks. 
• Torso: You suffer Disadvantage to all CON and STR checks. 
• Arm: You suffer Disadvantage to all checks that requires the use of the injured arm. If it's your shield arm, you cannot use your shield. If it's your weapon arm, you suffer Disadvantage to your attacks. You can still carry mundane light items with the injured arm (ie: torch, etc) 
• Leg: You suffer -10' speed(land) penalty as well as Disadvantage to all STR and DEX checks that requires the use of the injured leg. You can only travel at slow pace during exploration phase. 

TREATING AN INJURY

• When a body part is injured, the GM rolls a private (10-CON modifier)d10 and write down the number. This number represents the maximum number of days it will take for the limb to heal. 
• When you take a long rest, do a DC10 CON save. On success, remove the success variation to the number of days remaining + 1. On failure, the long rest did not help this time. If you have no physical activity whatsoever during the day before the long rest, do the save with Advantage. (note: If you roll 13, remove 4 days to the number of days remaining. If you roll 10, remove 1 day.) 
• When you take a long rest, you or another can do a DC10 Medicine check, using one Healer kit charge. On success, remove the success variation to the number of days remaining +1. On failure, the treatment did not help. There can be only 1 treatment check per long rest. 
• The spell "Lesser Restoration" has a new additional use: "Treat Limb". When used, remove (magic ability modifier)d10 days per cast. Each cast only affects one limb. 
• The spell "Greater Restoration" has a new additional use "Restore Limbs": When used, all injured limbs are immediately healed. 

Game-play example:

• During the fight with the dragon, Urist suffered a critical hit to the arm. The remaining HPs after the hit were lower than his 1/2 Max HP therefore he does a normal DC10 CON save. He rolls a 3 and fails, suffering a lasting injury to his right arm. 
• Urist has 15CON, therefore a +2 modifier. The GM rolls (10-2)d10 to determine the duration of the injury and the result is 43 days. 
• When he rests that night, Urist tries to treat the arm and does a Medicine(WIS) check, using one healing kit charge. He rolls 16. For the natural healing due to the rest, he rolls 13 on his DC10 CON save. In the morning, the GM removes 11 days to the remaining days (7+4) for an end result of 32 days. 
• The next day, Urist remains in bed, reading and praying. During his next long rest, he tries to treat the limb again. Grom "Help" him and Urist rolls 14 on his Medicine(WIS) check due to advantage, boosted to 17 using his Guidance cantrip. Then he rests and rolls 18 on his natural healing check due to advantage. The next morning, the GM removes 17 more days, giving 15 days remaining before his arm is fully healed. 
• The day after, the group moves on and Urist avoids having to use his injured arm whenever possible and is "Helped" by others when he needs to. That night, he treats his wound again before taking a long rest. Once again helped by Grom, he rolls 13 to his Medicine(WIS) check, boosted to 15 due to his Guidance, then rolls 8 on his natural healing check for the night. The next morning, the GM removes 6 days, leaving only 9 days.