"Light effects" in 2K2's spells

[Googi]

I always assumed that the lights in 2K2's spells were achieved using normal light/particle effects (I'm talking about things like the trail of light behind bullets, not the projectile GFX). However, I recently found that they're (mostly) still displayed even with lights/particles turned off (and thus must be something else or the disabling of lights/particles is being overridden somehow). I was wondering how these effects are achieved if not with lights/particles.