The following situation: 2 Members of the party try to sneak up on distracted enemies. The other two, not stealth proficient players want to stay 20 feet behind, not roll stealth and join after the others. The approach is fine by me, but I am really confused about how near they can get before being noticed. This is important because I need to know how long they will take to join the fight afterward.
If I had to guess, I would say there is a detection range, how far a creature can detect others. Is there any rule for that or does the DM have to arbitrarily decide every time? Also, how does the alertness of the detecting creature and the environment (i.e. reverberation in a dungeon) factor into this?
Best Answer
There isn't a hard rule, so it's up to the DM and table
Without explicit information about detection range, this becomes a table dependent judgement that will rely on environment, creatures, etc. In general, I do the horrible thing and try to think of real world scenarios to help guide me.
Does being 20' back make sense for the scenario? Are there places to be out of sight and sound?
Or is this a situation where the enemies can pick out problems from farther away for reason X?
Being reasonable, assessing the specific situation, and communicating with your players what you think is reasonable and getting them to buy in is how you should proceed with this.
You can use ability checks to help guide you, or use certain triggers that make sense for that environment for an ability check.
As long as you are reasonable, consistent, and communicate your plans, then these issues work themselves out at the table.