All right.  Fine.  I have devoted some time into the matter, and I have come up with a ruling.  No arguing.<br/><br/><div class="quoteheader"><div class="topslice_quote">Quote</div></div><blockquote class="bbc_standard_quote">However, as per RAW, as far as I can tell Tem - as the rider - counts as occupying all squares her mount occupies for the purposes of LOS, so that last bit shouldn't even be an issue.</blockquote><div class="quotefooter"><div class="botslice_quote"></div></div><br/>This is not true.<br/><br/><div class="quoteheader"><div class="topslice_quote">Quote</div></div><blockquote class="bbc_standard_quote">Big Creatures and Cover<br/><br/>Any creature with a space larger than 5 feet (1 square) determines cover against melee attacks slightly differently than smaller creatures do. Such a creature can choose any square that it occupies to determine if an opponent has cover against its melee attacks. Similarly, when making a melee attack against such a creature, you can pick any of the squares it occupies to determine if it has cover against you.</blockquote><div class="quotefooter"><div class="botslice_quote"></div></div><br/>As you can see, this would only apply to your horse.  It wouldn't apply to you.  And it would only apply to melee attacks, not ranged attacks.<br/><br/>GIVEN THAT, I will now rule that:<br/><br/>1.  There is not total cover.<br/><br/>2.  The goblin dog could not have charged, and therefore does not incur a penalty for charging.  This is just as well, since I never actually gave him a +2 to attack in the beginning.  Thus his AC is still 13.<br/><br/>3.  Any way you look at it, Faranal and his horse provide soft cover, but it doesn't actually stack.<br/><br/><div class="quoteheader"><div class="topslice_quote">Quote</div></div><blockquote class="bbc_standard_quote">To determine whether your target has cover from your ranged attack, choose a corner of your square. If any line from this corner to any corner of the target’s square passes through a square or border that blocks line of effect or provides cover, or through a square occupied by a creature, the target has cover (+4 to AC).</blockquote><div class="quotefooter"><div class="botslice_quote"></div></div><br/>This is how cover is determined.  So, if I choose a corner of your square, to ANY corner of the target's square, and there is an obstacle in between, then there is cover.  There is nothing in the rules that states that cover of the same type stacks.  Therefore, the goblin dog now has a +17 AC.<br/><br/>4.  Any way you look at it, the goblin has some sort of partial hard cover, which stacks with the soft cover.<br/><br/>Partial cover increases the dog's AC to +19 AC.  Much the same argument as above.<br/><br/><hr/><br/>Therefore, the AC for the crit'd goblin dog is 19.  Therefore, Tem crits, but fails to confirm.  This is the ruling.  Challenge it at your own peril.