The Bulezau’s Rotting Presence is one of the very few features that scaled with having more of those creatures in proximity. The scaling was negligible, but I do like the concept.Bulezau (MToF, BG
iA)
When you think of a generic devil, you probably think of some kind of goat-man. D&D has never been all that close with its source materials (save for maybe the writing of Tolkien), so the Bulexau are classified as demons instead. As beings of animalistic violence, they serve no particular demons other than the ones who just happen to bully them into servitude. Though they have been explicitly tied to Baphoment in the past, their current description has only a vague connection due to their similar natures.
In combat the Bulezau will rush to the front line and stab with their Barbed Tail. Using their Rotting Presence for some minor damage and hoping their victims are infected with the disease on their Barbed Tail. The second round is where things get a little more interesting. They have a standing leap that lets them jump 10 feet into the air and 20 feet horizontally, combined with a 40’ movement speed, this makes them somewhat harder to pin down than other brute-type monsters. They can simply jump over the heads of the front line warriors, and land on the other side without expending any extra movement or provoking an OA. This immediately opens up any targets in the second ranks to their onslaught, removes any cover that the front line was using them for, and can even prevent the front line from receiving support from the back.
The Bulezau are one of the few creatures that are deadly long after the combat is ended. If a target fails their saving throw against disease, they can be poisoned for days on end. It takes an entire 24 hours for the next check, and if they fail that one (or subsequent ones) they lose maximum hp permanently.
In the changeover, the Bulezau’s Rotting Presence was made more consistent, and their Barbed Tail attack was given more damage.
Makes sense that this is one of the rough edges that got filed off with the tighter design.