Been meaning to ask this for a bit, but I'm not currently playing a Drow character, and if I were I wouldn't be requisite level for Psychic Power yet.
According to the entry:
Drow Magic: Alien Archive pg. 43
"Drow gain the following spell-like abilities. The caster level for these effects is equal to the drow’s level.
At will—dancing lights, detect magic
In addition, drow count as having the Minor Psychic Power feat for the purpose of meeting prerequisites, and if a drow takes the Psychic Power feat, she can add the drow noble’s limning light supernatural ability to the list of spell-like abilities available to her."
The Limning Light ability on the prior page has no use limit I can see. No X/day or recharge on short rest.
Limning Light: Alien Archive pg. 42
"As a standard action, a drow noble can cause all creatures and objects in a 5-foot-radius burst to shed a pale glow. Creatures outlined by the limning light take a –20 penalty to Stealth checks and don’t benefit from the concealment usually provided by darkness. If an affected creature is benefiting from an effect such as invisibility, all others within line of sight of it become aware of its location (see page 260 of the Starfinder Core Rulebook). This effect lasts for a number of minutes equal to the drow noble’s CR (11 minutes for a drow noble arms dealer). This ability has a range of 100 feet."
So it creates a small triad of questions.
If I take Psychic Power, how does it all work?
Psychic Power: CRB pg. 160
"Select one of the following 1st-level spells: comprehend languages, detect thoughts, or mind link. You can cast this spell once per day as a spell-like ability, using your character level as your caster level."
Is Limning Light added to the Psychic Power list of spell-like abilities as a 1/day use?
Do they get Limning Light as the monster ability at-will in addition to one of the Psychic Power abilities? (The wording of "can add" in Drow Magic suggests this untrue, but I'm not 100% sure.)
Is a PCs CR equal to character level for determining the duration of the ability?
I've looked at it a few times and I'm still on the fence for it. I can see it going both ways, so if someone has some insight I'm missing it would be helpful.
Been a week, still no news on this one?
"...and if a drow takes the Psychic Power feat, she can add the drow noble’s limning light supernatural ability to the list of spell-like abilities available to her."
Based on that wording ('can add' not 'does add' specifically), my interpretation would be that if you took the psychic power feat, you select your choice of Limning Light OR the usual Comprehend Languages, Detect Thoughts, or Mind Link when you choose the feat. Regardless of what you choose, you can cast it 1/day.
Definitely not as clear as it could be, though.
Minor Psychic Power lets you cast a spell 3 times per day. Psychic Power gives 1 spell per day. Using a feat does seem like a big investment to cast a minor spell only once per day. As a GM, I think I might allow the 3 times per day, otherwise not sure anyone would ever take this feat? Also, you have to be at least 4th level, so by then, the spell list you can select from does seem insignificant. One 1st level spell per day? Wow. Most casters have at least 4 first level spells by then. And it’s the same field, you can’t change it or pick another.
My interpretation:
If you are a drow and take Psychic Power, you add limning light (as a spell-like ability rather than supernatural) to the list of SLAs you can choose from. If you choose limning light, you can use it once per day.