goatmeal |
Thanks for all the feedback everyone. I think maybe making the overall encounter an extra +2 CR might be right.
A bit more on the scenario. The players aren't going to totally understand the situation, and if they do choose to attack it from melee distance it will be very difficult to deal with. They might be motivated to do this, as it is using a device to bring more zombies to the room (there is a finite number of zombies that can be attracted in this way, but they aren't going to know that, and they would eventually encounter all of these zombies anyways). If they do stay out of range of the tendrils, then they are concentrating themselves into a smaller section of the room, making the zombies more difficult to deal with and increasing the likelihood that they will encounter more of them by allowing the bloody bones to keep bringing them in.