Using the PNP Darkness switch.
Darkness seems to apply an immediate darkness effect to equipment-less creatures and give a temporary darkness aoe itemproperty to an item in the inventory of a creature with equipped gear, however this latter function is not immediately evident, and does not seem to manifest itself as an effect until the equipment item is un-equipped and re-equipped.
Naturally, for the purposes of calling down darkness on enemies, this is ... suboptimal. However, in all cases of Darkness cast on a creature, once it is in action, the Darkness is gratifyingly mobile with the creature.
Also, Darkness seems to be castable on the ground, but produces no effects; Darkness does not seem to be castable on placeables.
I thought that it ought to produce a stationary darkness AoE if cast on the ground, an immediate and mobile darkness AoE if cast on any creature, and an equipped-dependent mobile darkness AoE if cast on an equippable item in the caster's inventory. (It would be an unhappy state of affairs if the hostile target of Darkness could simply unequip the item causing darkness; while I know that unequiping armor (the default equipment target) isn't allowed in combat, the scripting seems to suggest that it will cycle through all possible equipped gear before applying the effect to the creature itself -- certainly this seemed to be the result in my self-casting testing.
