So two things. First, I think you're trying to bring realism, simulationism, and verisimilitude into a gamist system. That doesn't work that well. The system abstracts a TON of things. We just need to decide on rules. In no way whatsoever do they need to actually follow "reality". Having to follow "reality" in every case would make the system very clunky, boring, and make the rules take hours as we tried to take real-world effects into consideration. No need for that whatsoever in my opinion.<br/><br/>Second, just go with whatever the DM rules. Let's pretend the moonlight/starlight case is an actual issue. He could decide a few things:<br/><ul class="bbc_list" style="list-style-type: decimal;"><li>There is enough light for no one to have concealment.</li><li>Characters gain concealment. Characters with low-light vision ignore this concealment.</li><li>Characters gain full concealment. Characters with low-light vision consider this to just be concealment.</li><li>It is dark enough that all characters gain concealment.</li></ul>Then add in ranges if he wants to, though the light is uniform so I think you can dispense with that.<br/><br/>He could justify this in any number of ways (very few stars visible, cloud cover, some astral phenomenon that stops us from seeing the light as well, whatever), but those don't matter too much in the end for the most part.<br/><br/>Regarding the combat aspect... I don't think my character is in range for the spell (Close range), so she'll simply try to get into range and then to use it.