An issue came up at SCG Regionals in NC a few weeks back that involved Collected Company, Hallowed Moonlight, and Athreos, God of Passage. Assuming that there is an empty board state when Collected Company is cast, will Hallowed Moonlight prevent Athreos from entering the battlefield? I know that a Rules Blog was written regarding the gods and Imposing Sovereign here, but I’m wondering if Hallowed Moonlight’s effect works differently from Imposing Sovereign. Rule 614.12 deals with how a creature should enter the battlefield (and thus wants to know the characteristics of the permanent on the battlefield), but my reading of Hallowed Moonlight seems to indicate that it is instead dealing with the issue of if a creature will enter the battlefield. I understand that if Rule 614.12 applies in this case that Athreos would be placed on the battlefield (assuming an insufficient amount of devotion) because Hallowed Moonlight would not affect Athreos. What I’m wanting to understand is if there are other rules or interactions that could apply well to this situation. Chord of Calling and Birthing Pod are both other cards that would interact with Hallowed Moonlight and the gods in this way so there are several ways that this could come up.

I would greatly appreciate a fficial answer to this, but I look forward to any discussion along the way–this has been an excellent way for me to further my thinking and understanding about replacement effects. If you have any questions about the scenario as I'm presenting it, please feel free to let me know as well.

PS–I have to give a big thank you to Clayton Price who has discussed this issue with me over the last few weeks and has helped me deepen my thinking about replacement effects!

614.12 applies to Hallowed Moonlight exactly the same as it applies to Imposing Sovereign. Under the Moonlight, a Theros God that's entering the battlefield off of a Collected Company (or Chord of Calling, or Birthing Pod, etc.) will be exiled if and only if its controller already has sufficient devotion to the appropriate color(s) on the board for it to be a creature. The God's own mana symbols are not taken into account, nor are the symbols of any other permanents that happen to be trying to enter the battlefield at the same time.

So in the given situation, with Athreos arriving onto an empty board, Hallowed Moonlight will not apply, and Athreos will enter the battlefield unhindered.