Reaction Rolls for Modern D&D

While reaction rolls were a staple of old D&D, their reliance on a different way of interpreting Charisma modifiers has made it difficult to re-introduce them to modern D&D. To correct this, I have recalculated the old reaction tables to provide the same probabilities as they did then, but by directly relying on PC Charisma scores. 

Other than the adjustments to work with modern math, these rules are mostly identical to those found in BECMI D&D.

Also, I've been thinking a lot about reaction rolls for a more serious project, and sometimes solve math problems to calm myself down. It seems like my nervous habit might be useful for other people, in this one weird case, so... here you go. 

P.S.: I specifically calibrated the math on this for ability scrolls that are rolled 3d6 straight down. Which... is not how 5e works.