Help with Determining Resonant Reflection power

[Flames of Chaos]

I've been playing Extinction curse with a monk since level 1, and I've mostly been ignoring the Reflection of Light(?) you get that gives you darkvision and Searing Light once per day. That being said, I'm getting tired of not being able to contribute to ranged combat and would like to figure out how to use it as I'm not sure if the spell part of the power heightens?

My monk is using Occultism for his tradition, as he has a couple of Ki spells. Do I use Occultism + level (15) plus charisma (sadly 10, so mod 0)? What level do I count the spell at for purposes of heightening it (if any at all) since the spell is technically innate?

Rules for innate spells here:
https://2e.aonprd.com/Rules.aspx?ID=259

I'm having problems because of this section under "Innate spells":

"You can't use your spell slots to cast your innate spells, but you might have an innate spell and also be able to prepare or cast the same spell through your class. You also can't heighten innate spells, but some abilities that grant innate spells might give you the spell at a higher level than its base level or change the level at which you cast the spell."

Thanks in advance!

[CharlieIAm]

The Reflection of Light specifies that it is heightened to half your level rounded up (similar to a cantrip). You use your Spell Attack proficiency bonus + Charisma mod to hit.

[thewastedwalrus]

Yep, also worth mentioning that "You're always trained in spell attack rolls and spell DCs for your innate spells, even if you aren't otherwise trained in spell attack rolls or spell DCs. If your proficiency in spell attack rolls or spell DCs is expert or better, apply that proficiency to your innate spells, too. You use your Charisma modifier as your spellcasting ability modifier for innate spells unless otherwise specified."

So you'd be trained in it unless you have expert+ spells from something else like your class.