The errata posted yesterday says the enemy needs to see you clearly. That is a fact you are choosing to ignore. Being obscured by an ally allows you to hide. The rules are crystal clear after yesterdays errata.
That hilarious because to me the errata proves my point, not yours. In fact, when I first read it I praised Jesus for an end to all the argument.
I'll paste it here exactly so we can examine it.
"Hiding (p. 177). The DM decides when circumstances are appropriate for hiding. Also, the question isn’t whether a creature can see you when you’re hiding. The question is whether it can see you clearly."
So 1) read the first sentence.
2) read that first sentence again so you understand it.
3) read it one more time.
Now if YOU want to rule that a light foot halfling can hide behind a human when an Orc can CLEARLY see them doing it, more power too you, DM. That first sentence lets you do so.
But I think you are doing that based on some bad assumptions. One is that being behind the human is equal to being heavily obscured. Since the rules state that heavy foliage constitutes heavily obscured, I can see where you are getting that, but the wording refers to an area, not a creature. A creature can't be heavily obscured, and that human you are hiding behind is not heavily obscuring the entire area so much so that the Orc is effectively blinded.
The Orc can still see you as you move to your position behind the human.
Now looking at page 176(I've a feeling you have not read this page despite my numerous appeals) it says that "until you are discovered" your stealth check is opposed the wisdom perception check of any creature actively searching for "signs of your presence". A good "sign of your presence" would be the face that they just CLEARLY saw you go behind the human. At this point, before you have even rolled you stealth check, you have been "discovered".
The second paragraph in addition to the oft quoted "you can't hide from a creature who can see you" the same sentence goes on to say "if you make any noise you give away your position." My take on that is that if you have given away your position, then you have been detected and thus you are not hiding. Just as in the Monte Python video, although you may not be "SEEN" that Orc KNOWS you position. He is not that stupid (and hopefully neither are the DMs judging these situations).
Now the very last sentence in that green box (still on page 177 of your players handbook... Stay with me now) is that "one of the main factors in determining whether you (in our example, the Orc) can find a hidden creature or object is how well you can see in an area, which might be lightly or heavily obscured"
Here's the thing. The Orc saw you go behind the human, or he saw you pop out and shoot at him last round. Thus you are not a "hidden creature" and no check is called for. You are a creature whose position is known to the Orc.
The reason for the errata is to both codify the Mike Mearls tweet that it is ultimately the DMs call (part 1) and to clarify that IF the environment offer something like fog or light rain, or dim light, then we have a question of whether or not the Orc could CLEARLY see you move behind the human, or pop out to fire a bolt and pop back. That is the ONLY CIRCUMSTANCE where you would be able to hide from someone who can already see you. In the cold light of day your chances are ZERO. the errata backs me up on this, it does not refute it.
