Corners and Cover

[Kordeth]

So by extension, the PHB's "you have cover when your attacker is the around a corner", wording is really an exception to cover rule that only applies to melee attackers, correct? If you are more than one square "around the corner" I don't think this would be an issue, since there is an obvious obstruction.

You're getting hung up on one potential example of when a character might have cover and assuming it's a global rule. The rules for determining cover are presented under "Determining Cover," what you're quoting is just a description of what cover can entail.

Basically, in this situation, the wizard is "around the corner" from the goblin (and thus has cover against the goblin), but from the wizard's perspective, the goblin isn't around a corner at all, he's standing right out in the open.

 

[frankthedm]

Looks fine to me. The caster chooses a corner of the origin square to draw the lines of cover determination.

http://img247.imageshack.us/img247/1742/covfc2.png

 

[deleteme123456]

For what it's worth, the attached diagram shows an example where the origin square difference is important.

The red line is a wall. Since the origin is in the wizard's square, a lot of the squares have cover (2 are shown with purple and black lines). If instead the first square adjacent to the wizard was the origin (it's not, but some people might think it is), then you could pick the "bottom" edge of the red wall as the corner to use for cover checks, and you'd be fine to every square in the blast.