IanB said:When talking about cover, large+ creatures actually typically have an easier time getting it against ranged attacks. Remember, the 'choose one square' rule for cover with larger creatures is for melee attacks, not ranged attacks. With ranged attacks, you have to trace to every corner of every square of the large+ creature to check cover. Terrain counts as well.
Actually, this is not quite accurate.
The actual rules quote is:
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).
This states "square". Singular.
This says nothing about creatures that occupy more than a single square.
The following quote:
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.
This rule says nothing about ranged attacks.
Hence, we have no rule (TMK) that discusses ranged attacks versus large creatures. The rule just does not exist.
So, a DM can make up a rule, or use one of these two rules. At a range of 5 feet, I see no difference between melee attacks and range attacks for the second rule. Creature A is attacking large creature B from the same square with either a melee or ranged attack, so why should the cover rule be different? Does the wall to the archer's left stop arrows when he is firing to the right, even though it would not do so for the fighter swinging his sword?
The second rule also makes more sense. The colossal dragon should not be able to hide behind a human, any more than an ogre should be able to hide behind a mouse.