Stormonu
NeoGrognard
open-ended fumbles and crits. It's a system I've used since 2E.
On a roll of 20, you roll again and can get a 2nd success if you meet or beat the target number again. Another nat 20 continues the process. (I use this so if you needed a 20 in the first place to hit, it's much harder to get a double-success). In the case of saves, a second save allows you to give the extra success to an ally who may have failed the save or if the effect only targets you, rebound it back to the individual who caused the save.
Similar on a 1; automatic miss and roll again. If you don't get a success on the 2nd roll, you open yourself up for opportunity attacks or other bad things to happen.
On a roll of 20, you roll again and can get a 2nd success if you meet or beat the target number again. Another nat 20 continues the process. (I use this so if you needed a 20 in the first place to hit, it's much harder to get a double-success). In the case of saves, a second save allows you to give the extra success to an ally who may have failed the save or if the effect only targets you, rebound it back to the individual who caused the save.
Similar on a 1; automatic miss and roll again. If you don't get a success on the 2nd roll, you open yourself up for opportunity attacks or other bad things to happen.