Рыцарь Бездны
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By the way, I forgot to mention: this lighting should be in the Ground/UnderGroundAmbientLights list in the Map Properties Tree. In Runes, the line SetAmbientLight(GROUND, "NecromancyFog", true, 3) worked, so the issue is with the point mentioned above.
It worked! You were right, I added a few more lines to GroundAmbientLight, specified all the desired lighting in them, and now everything works. The FPS drops slightly during the lighting change, but it's worth it; the location really comes alive with all this.