Dark desires flowing from the human heart, forming a night darker than night itself?
Interesting.
If I sort out the timeline, one thing is certain: the Night Potion appeared before the first Desecration of the Sun.
So, a simple logic suggests it was intended to be at the core of the plan, meaning that Gulad's people believed it was a means to an end.
However, because of their own act of desecrating the sun, Gulad's bunch decisively gave up on confronting the new city official and instead started to behave more discretely, opting for limited private distribution.
There are two explanations for this behavior. The first is that they were inspired and completely changed their strategy.
The second possibility is that the phenomena they demonstrated before made them think that limited distribution was enough.
Right now, the second possibility clearly seems much larger.
In other words, the scene before us is the miniaturized version of what Gulad wanted to achieve.