I hear what you're saying, but I keep tripping over the fact that you're complaining over not being able to murder two half devils which a full grown mindflayer is struggling with who, by the way, has more than tne 7-9 paltry hit points my character has. That thing looks at me funny or sneezes in my direction and I'm toast. It makes perfect sense that you cant get your characters to work together to kill those things, because they realistically realize that they are severely outmatched and their best chance of survival is to do what the mindflayer said and use the transponder to gtfo of there.
It is not uncommon for DMs to make certain things impossibly difficult in order to steer the party in a different direction. Particularly a direction that better suits their level.
