I'm so sick of people attributing the complaints to people not understanding random - did you guys even play the game? Eldritch Blast regularly misses to me, even on high % hit chance, this happens ALL THE TIME, NOT JUST SOMETIMES!
And it goes the other way around, too, I can send Karlach in with confidence of her hitting at least one of the two hits, mostly both, if I send her with a reckless attack+great weapon master at something with a 34% hit chance.
The numbers might not be rigged, but they sure as shit aren't correct, either.
It's a 1 Dice roll against, like say 15 DC enemy.
your probably +3 Charisma + d20 vs 15 DC --> you *will* miss *a lot* without advantage. That number will be increased two fold when you get the second blast.
Make sure Karmic Dice is OFF (especially after Big Patch), I also having less "consistent" hit while playing Warlock when its ON.
