This is a foundation/mid level article on Signs and Portents. The gentlemen on MoM posed a question on Podcast 11. Here’s my stab a response.
Does Signs and Portents affect your chance to roll a critical attack?
The short answer is yes. I’ll walk you through the intuition behind it and then give you a few pretty pictures with math to show you that I’m not a liar.
Critical effects occur when dice outcomes on two or more dice are the same AND the sum of the dice is sufficient to hit the target. In an earlier article, I talked a bit about intersection probabilities and that’s what we’re looking at here. What affects the odds of rolling doubles? What affects the odds of rolling sufficient to hit a target? Critical effects are impacted by either scenario because they are at the intersection of the two components.
Signs and Portents increases your average result on two dice from 7 to 8.46. As a result, your intuition should be that it increase your critical effects through the “increased likelihood to hit” pathway.
If you apply brut force to the math and write out every possible combination of dice outcome you’ll see that more high pairings occurs as a result of the spell ([5,5] and [6,6]). You approximately double the likelihood of rolling boxcars when rolling 3d6 minus the lowest versus straight 2d6. Fun.
PerfectCircle from the Focus & Fury boards put together a great graphic showing all the iterations of dice and attack rolls you might care about. It’s frankly a lot prettier than the one I put together so I’m going to use it. PerfectCircle, you are a both a gentleman and a scholar. Thank you. Here it is;
The more you know… (hum the little diddy in your head when you read this last part)