Generally darkness spell effects are pretty weird, and even using the usual "it's just magic" explanation, it's hard to relate these to the real world. I think we agreed at one point that darkness spells used some sort of anti-photons to produce their effects. We shied away from the whole anti-photon hits a photon interaction discussion. In the end, it's just game mechanics, and doesn't matter.
Rule clarifications are:
- dark/light spell effects suppress any light/dark spells of lower levels in their area of effect
- dark/light spell effects and light/dark spell effects of the same level suppress eachother in their overlapping areas of effect, leaving any lower level and natural light or darkness spell effects in effect.
- dark/light spells can be used to counter or dispell light/dark spells of equal or lower level at time of casting.
- standard ride checks apply when using a Phantom Steed (spell) except for "Control Mount in battle" as it wouldn't get spooked by battle, and "Fight with a combat-trained mount" as it isn't combat trained.