I'm not sure a horror movie villain having brainrot is a good thing or a bad thing.
Very bad. You cannot fight her, her constant word diarrhea will confuse you so much, you won't even notice she's stabbing you. Worst case, you'll become a ghost doomed to wander your house until someone translate what she said to you as she murdered you.
The mouther babbles incoherently while it can see any creature and isn't incapacitated. Each creature that starts its turn within 20 feet of the mouther and can hear the gibbering must succeed on a DC 10 Wisdom saving throw. On a failure, the creature can't take reactions until the start of its next turn
I'm not sure a horror movie villain having brainrot is a good thing or a bad thing.
God, I really hope this is played for comedy and his GF isn't actually some kind of alien/horror that's being kept subdued with zoomer brainrot or whose first consumption of human culture was zoomer stuff.
Dear god. And the mimic in Baldur's Gate 3 already spooked me enough that I swore intensely.
Thankfully, 5e gibbering mouthers are not that strong. They do an absolutely ludicrous amount of damage for such a low-level monster, but they have poor AC, you're probably going to succeed on the save to avoid getting whammied by the Gibbering effect, and they only have +2 to hit.