So I'm playing around with the idea of giving some low CR creatures a fear aura. I want to give more of a mechanical flavor to the creepiness of undead.
First, I'm trying to figure out what CR value to apply to giving, say a basic skeleton, a fear aura.
How it would work would be: fear aura 10' - DC 11 Will save or shaken while in aura.
There is a great deal of variation on what you can do with a fear aura, from making it shaken, all the way up to panicked, and then there is range, duration, etc.
So part of it is simply figuring out a metric for the CR value. Since these are low CR creatures, there isn't a lot of granularity so I'm just adding +1 CR for the moment.
The second issue is the stacking up of fear auras. So if you have several skeletons attacking a PCs, all of the auras are overlapping the PC, resulting in multiple saving throws. That's fine, as I'd like the effect to be that if a swarm of scary things attack a PC then it is possible for the PC to move from shaken, to frightened, to panicked, and even in dire situations become cowering. The skeletons themselves are pretty easy to smash apart, it's having a large number of them coming down on the PCs that unsettles them, filling the air with dread at their own mortality.
So part of it is an issue of convenience. I want to figure out a way to easily do these fear effects so that who needs to roll what and when flows well, and also take into consideration how that affects CR values.
At first I thought that tying fear effects to getting hit by a skeleton would work, that way Will saves only happen in specific circumstances, however the PCs will quickly get to a point where the skeletons won't have much of a hope of rolling to hit and thus essentially negating the fear effect.
The other easy way is to just have a will save every round while in an aura. It's ok, but it makes the fear effect really potent at a certain point, as it would average out to about five rolls over the course of a battle, giving plenty of chances to cause the fear escalation. I'm just not sure that is worth just +1 CR.
