So, disadvantage. I rolled a dwarven warlock with Charisma of 15 and let him attack the AC7 enemies with his eldritch blast from close distance. At a reasonable distance, this would be a 90% chance (+4 attack bonus vs AC of 7 = need to roll a 3 to hit). However, with disadvantage, which forces us to take the lower of two attack rolls, it's but a 81% chance. Contrary to the advantage test above, it should also increase the likelyhood of critical misses rather than critical hits (spoiler: it did). https://statmodeling.stat.columbia.edu/2014/07/12/dnd-5e-advantage-disadvantage-probability/
This much in advance, this time I was getting reasonably lucky, not so much at the start, but later on.
2 miss 11 hit 7 hit 8 hit 5 hit 11 hit 2 miss 4 hit 14 hit 3 hit 13 hit 12 hit 16 hit 9 hit 11 hit 3 hit -------------------- 1 critical miss 19 hit TWO CRITICAL MISSES; WHAT PEOPLE MAY REMEMBER 6 hit 1 critical miss 2 miss ---------------- 10 hit 8 hit 16 hit 3 hit 12 hit 8 hit 8 hit 7 hit 7 hit 16 hit 6 hit 7 hit 13 hit 12 hit 16 hit 15 hit 29 HITS IN A ROW -- WHAT PEOPLE WON'T REMEMBER 8 hit 5 hit 4 hit 9 hit 5 hit 8 hit 11 hit 3 hit 3 hit 15 hit 7 hit 9 hit 5 hit --------------------
TOTAL ROLLS :50 TOTAL HITS: 45 TOTAL HIT RATIO (90%)
At least 100 throws would naturally be a better data set (sample size). Unless I just mistyped, the 29 hits in a row on a 81% chance are a 1 in ~450 chance which should not be that common, but will happen a very reasonable amount of time if you consider the number of rolls on a night, even a playthrough or even multiple playthroughs. Edit: Speaking of which, loading the save and doing my next four attacks immediately rolled two critical misses, so there.
