Two Stats as a way to empower D20 Roll under actions

homebrew
#1

So I’ve had the idea of using combined stats to determine the proper bonus for any action for a while, but haven’t really felt like it was where I wanted it, but this morning I had this idea: for D20 roll under your stat mechanics, you can apply all the rules normal, but add a second stat into the mix; if the player rolls below the higher of the two stats, apply rules as normal, but if they roll below the lower of the two stats, they get some benefit -max damage, damage+effect (trip, disarm, pin, etc.).

As an example, we can use a ranged attack. Berk is attacking a wicked knight with his crossbow. Berk has a 13 DEX, so that’s his target to hit. The GM add that if the player also roll below Berk’s 8 WIS, he sees the gap in the knight’s armor, and gets MAX damage on the hit. So, 13-9 is a regular roll for damage, and 8-2 is MAX damage (or some other benefit, if you prefer).

I do recognize that this idea sort of relies on significant differences in the stats. A PC with 12-9 down the line is gonna feel weird about getting a significant benefit from rolling marginally better on a D20, so this may require slightly different sat generation, or PCs with stat arrays. Anyway, curious what people think of the concept.

The Stunt Die
#2

It sounds like something that needs play-testing for two aspects :

  • Does it make fights slower ?
  • Does it take more processing power on the player part ?
    Also, it’s not really something the players have any control on. You could make it more of a gamble with the player choosing the die they want to roll as a second roll with different degrees of added bonus depending on them. Gambling a full on D20 ? You might crit ! Gambling a d12 can add a little spice. Gambling a d16 (or equivalent) might add more spice without being strong as a crit.
#3

I was thinking of it as all in one roll, but what I hear you saying is for bonus effects, you have to roll a smaller die type? Of course, with a roll under mechanic, that increases chances of success, rath than decreases - but the idea is sound. They could just roll a D24, 4d6, 2d12, or a D30.