Blast and adjacent area

[Alnag]

Well, I always assumed that adjacent area means adjacent to a character in any way possible by any corner or any square side of any part of blast. Than one of my players playing in other group as well proposed, that the only possible "adjacent forms" of a blast are those presented in PHB p. 272. That means you are either on the corner of the blast or in the middle of the whole side of the blast area (in case of blast 3 it is the second square in case of blast 5 it is the third one).

I am not sure if there is any blast with even number like blast 2 or blast 4, but basically, I am somewhat unsure on this issue. So can it look like this:

C
XXX
XXX
XXX

XXXXX
XXXXXC
XXXXX
XXXXX
XXXXX

Thanks for any answer...

 

[Kordeth]

Your player is incorrect. As long as the blast is adjacent to the origin square and does not include the origin square, you can place the blast wherever you want.

 

[Rafe]

Your player is incorrect. As long as the blast is adjacent to the origin square and does not include the origin square, you can place the blast wherever you want.

Exactly, and well put.

 

[Alnag]

Thanks a lot!

 

[Doctor Proctor]

p 272 of PHB states:

Blast: A blast fills an area adjacent to you that is a
specified number of squares on a side. For example,
the wizard power thunderwave is a blast 3, which
means the power affects a 3-square-by-3-square area
adjacent to you. The blast must be adjacent to its origin
square, which is a square in your space. The origin
square is not affected by the blast. A blast affects a
target only if the target is in the blast’s area and if there
is line of effect from the origin square to the target.

So, other than the fact that they used a Close Blast 3 in the diagram, there's nothing in the PHB that specifies it must be a specific orientation. It only has to be adjacent, which means that it must touch either a corner or a side of your square. Also, you must have line of sight to any square affected.

ccccc
cbbbc
cbbbc
cbbbc
ccccc

In the above, "b" represents the blast area, and "c" would be any eligible spot for a character to fire the blast from.