Abilities for general task resolution (2/2)

Yesterday, I wrote about a mechanic I found in the Ready Ref Sheets for resolving extraordinary character actions. If, instead of using the uniform distribution of a d100, you use bell curve probabilities by adding d6's, you can tune the odds without resorting to +/- bonuses. Higher ability scores are relatively more helpful with this method, and you can use the mechanic to resolve both ordinary and extraordinary actions.

	9	12	15	18
2d6	83.3%	100%	100%	100%
3d6	37.5%	74.1%	95.4%	100%
4d6	9.7%	33.6%	66.4%	90.3%
5d6	1.6%	9.8%	30.5%	60%
6d6	0.18%	2%	9.7%	27.9%
7d6	0.01%	0.3%	2.2%	9.4%
8d6	0%	0.03%	0.38%	2.4%

A fighter with a 15 strength want to roll back a large boulder. The referee decides that it's a quite difficult task, so the player must roll under his strength using 6d6. However, if the character spends a turn digging dirt from under one side of the boulder, the referee can let him roll 5d6 for his next attempt.