So apparently we've been doing critical hits wrong in D&D.
A roll of 20 on a d20 is always a hit, and a "threat" aka Critical Hit. We knew this.
Apparently extending the "threat" range from 20 (so like.. 18-20 on a Scimitar) does not make a roll of 18-20 an automatic hit.
You still need to roll higher than the target's Armor Class, which changes how we were doing it drastically, lol.
Oh, and when it says Critical x3 or whatever, we would just multiply our rolls by that number. Turns out you have to roll your damage dice more, instead of just multiplying your initial results.
It makes more sense to do it that way, and allows for more consistent damage, but still..