I'm reading through the Waterdeep: Dragon Heist adventure. On page 28, there's an encounter with
Nihiloor the mind flayer. Note that Nihiloor is CR7 and the characters are first-level. Any hit from Nihiloor will drop a player character.
When the group bursts into Nihiloor's hideout, it: "rises from the stone chair, sets its pet [an intellect devourer] down, and glides across the room, intending to leave through the double door in the west wall. The mind flayer expects [its minion] Grum'shar and the intellect devourer to cover its escape.
This seems so lame!
The player characters are in Nihiloor's base, killing its minions. Nihiloor could kill them easily, but instead it abandons its minions, expecting them to cover its completely unnecessary escape.
I'm confused, because I don't understand why the villains are acting this way.
As a DM, one principle I try to stick to is that the characters' actions should matter. But this development seems to contradict that pretty strongly. I'm worried that running this encounter will make the group feel like their actions don't matter, because they're grossly outclassed by the villains and the villains simply don't care enough to kill them.
I understand that one explanation for the villain's behavior might be that
Grum'shar has just captured and tortured an innocent civilian, so Nihiloor thinks letting adventurers kill him will just save it the trouble of killing him itself.
I also understand that, in this adventure, the villains "don't really want" to kill the player characters -- but it seems to me that catching the player characters attacking their base should be an exception.
In your experience, what's the best explanation for the villain's motives here? What's the best way to run this encounter?