Absolutely agree with what Piotr said. A Warning is not something a player
should be worried about as long as they correct the behavior that warranted
the penalty. If Ashley doesn't make a habit of forgetting to reveal her
morphs (which in most other cases would be much much worse for her) then
she shouldn't have any concerns about this Warning, and we as judges
shouldn't have any concerns about issuing Warnings when they're appropriate.

Now, with the recent announcement, unrevealed morphs at the end of the game only result in a Warning, not an upgrade to Game Loss. Same answer as before for this scenario, just with simpler reasoning.

This seems like fishing to me. Clearly it's not a GL. I think that most players are aware of the “failure to reveal morphs rule,” but with my players at least they don't mentally file it as “GRV” (a lot of them aren't even aware of GRV as a technical term) and think of it as its own, freestanding rule. You don't reveal a morph, you get gamelossed. Explaining that it's actually just one application of a much broader principle is important, I think, because then you can avoid situations like the above, where the spirit of the rule is clear from a more complete understanding.

As many of you noticed this has not been a game loss neither before nor after the recently published change in the IPG. Before the situation was as follows:Ashley forgot to reveal her morphed Ashcloud Phoenix which is a Game-Rule Violation since c.R. 707.9 was broken. The IPG tells us that “An error that an opponent can’t verify the legality of should have its penalty upgraded. These errors involve misplaying hidden information, such as the morph ability or failing to reveal a card to prove that a choice made was a legal one.”. In this case none of the two examples applies since both players know what the face-down creature actually was when it was returned from the graveyard face-down so there is no point at which the legality of that creature being on the battlefield face-down was questionable and thus the infraction should not be upgraded.
The new language can apply when an unknown Morph isn't revealed.

(Note: this is the Knowledge Pool team's official answer.)

Edited Scott Marshall (Dec. 17, 2014 05:16:55 PM)