LOL! Mr_Grumpy_Face posted this awesome Dungeons & Dragons bard vs beholder story to r/DnD about how a 7th level bard singlehandedly took out a beholder without even rolling initiative:
Source: Mr_Grumpy_Face
Bard vs Beholder – Dungeons & Dragons Story
pretty sure bag of holding doesnt have oxygen in it so it can’t be used as party transport – beholder would have died in mouse form in minutes.
Same end result though, mouse form dies, reverts to Beholder and overloads BoH…
AFAIK there’s never been any official ruling on what exactly happens to things inside a bag of holding. I’ve always preferred to consider them in a timeless Statis field, not unlike what Dormamu had in the Doctor Strange Movie. Downside is it lets players transport living beings if they can fit them into the bag. Upside I never have to deal with “So I shoved three tomatoes into the bag years ago” ever again.