How do you DM with creatures that have kill requirements? /u/Cheep_thehomelessman DnD: Roll for Initiative!

For more context, I am a DM of a homebrew campaign. The BBEG and the gatekeeper boss of my campaign are creatures that can’t naturally be killed unless only very specific pre-requisites are met.

Without spoiling anything, I do know that “Shine Beyond the Witchlight” also has the same thing with one of its creatures.

As a DM, do you let your players know ahead of time that this type of mechanic is in play for the campaign or do you overly hint at it through the game?
I have tried overly hinting at these aspects before but my players never took any of the warnings and just trying to gauge how to adjust DM-ing style so that they would.

For more context, I am a DM of a homebrew campaign. The BBEG and the gatekeeper boss of my campaign are creatures that can’t naturally be killed unless only very specific pre-requisites are met.

Without spoiling anything, I do know that “Shine Beyond the Witchlight” also has the same thing with one of its creatures.

As a DM, do you let your players know ahead of time that this type of mechanic is in play for the campaign or do you overly hint at it through the game?
I have tried overly hinting at these aspects before but my players never took any of the warnings and just trying to gauge how to adjust DM-ing style so that they would.