How to create the illusion of dark light?

Since i updated my Project from 4.14 to 4.15, i noticed that setting a light “Intensity” of negative value doesn’t work anymore for the “black light” effect.

If i set Intensity to -10000 The light behaves like it’s clamped to zero intensity. (■■■■, this was not a bug, it was a feature, ■■■■ u 4.15 >_<)

However, i used it for just one scene in the game…

The giant door to the dark castle opens, and there are some particle effects and a really “bright” black spotlight behind the gate, and it creates this really creepy “OMG THERE IS EVIL STUFF GOING ON” look.

Okay, question: how can i fake this? Or how can i change the engine to allow negative intensity values again?
The biggest Problem is the opening of the door. how can i archive dynamic light without using dynamic lights?

Have you found the answer for this?
I’m with the same challenge now and trying to figure out.