TallIan
Explorer
Had you read the thread you linked fully, you might have noticed that I'm very active in it. I argue against the above interpretation as technically incorrect, but somewhat useful.
To hit you with disadvantage at a 2, my chances to hit go from 20/400 (1/20) to 39/400. That's a change of 19/400.
At a 11, the chance to hit go from 200/400 (1/2) to 100/400 (1/4). A difference of 100/400.
At a 20, the chances to hit go from 20/400 (1/20) to 399/400, a difference of 379/400.
Disadvantage has the largest effect at 20.
Parceling out damage as some fractional per round value is misleading. If you're hit by the giant, you don't take a fractional amount of the 29 damage. Dice do, over time, trend to the trend, but any given roll doesn't care what was last or what is next. So, at an 11, disadvantage halves your chance of being hit. That's nice. At a 20, though, it's almost 20 times lower. If you have the choice between giving disadvantage to a target number of 11 or one closer to 20, you'll always get more effect out of the higher target number. Any reduction is good, of course, so hitting the giant with disad when he's pounding on the mage is still a nice thing, but if you have the choice between having the mage hold the door while blurred or the fighter, the size of the "effect" is obvious.
I must admit I did not follow that thread very closely, as the OP of that thread was repeating information he had posted in another thread that I was more involved in, but it was less specific to ADV/DIS mechanic.
However, the effect I’m looking at in this case is that of damage taken - the product of to hit and damage rolled. I don’t care about the % decrease of the to hit probability.
To that end I ran a little white room simulation: 5 rounds of being attacked by a d12+6 damage run 20 times
Requiring a roll of 2 to hit Damage went from 61.15 to 57.6 therefor disadvantage saved me 3 or 4 HP’s
Requiring a roll of 11 to hit Damage went from 31.7 to 14.65 therefor disadvantage saved me 17 HP’s
Requiring a roll of 20 to hit Damage went from 6.3 to 1.4 therefor disadvantage saved me just shy of 5 HP’s
Now which of those three has the bigger effect? Which would you rather take?