My recent meditations on roll under ability checks and rant against the D20 unified mechanic has generated a bit of commentary and further clarified my own thinking on the matter. This post is an addendum to my  Using Ability Checks in B/X  article, seeking to further explicate why the "Roll Under" ability check truly is the best of ability checks. Earlier today, during my delvings into the blogosphere, I came across this box from  Quarrel & Fable , a Fighting Fantasy spinoff: First thing that struck me was how similar it was to my proposed resolution for Ability Checks . And secondly, it combined those thoughts with my memories of the old Fighting Fantasy  [FF] gamebooks and set my mind spinning into that cross section and how much I always liked the elegant simplicity of the FF mechanic. The best part about doing a post involving Fighting Fantasy is the chance to showcase some of the brilliant art in the gamebooks Now, I've given reasons already in previous posts